Hardenize Report: protonmail.com

Web Security Overview

HTTPS

Web sites need to use encryption to help their visitors know they're in the right place, as well as provide confidentiality and content integrity. Sites that don't support HTTPS may expose sensitive data and have their pages modified and subverted.

For all sites VERY IMPORTANT medium EFFORT

HTTPS Redirection

To deploy HTTPS properly, web sites must redirect all unsafe (plaintext) traffic to the encrypted variant. This approach ensures that no sensitive data is exposed and that further security technologies can be activated.

For all sites VERY IMPORTANT low EFFORT

HTTP Strict Transport Security

HTTP Strict Transport Security (HSTS) is an HTTPS extension that instructs browsers to remember sites that use encryption and enforce strict security requirements. Without HSTS, active network attacks are easy to carry out.

For important sites VERY IMPORTANT medium EFFORT

HSTS Preloaded

HSTS Preloading is informing browsers in advance about a site's use of HSTS, which means that strict security can be enforced even on the first visit. This approach provides best HTTPS security available today.

For important sites VERY IMPORTANT medium EFFORT

Content Security Policy

Content Security Policy (CSP) is an additional security layer that enables web sites to control browser behavior, creating a safety net that can counter attacks such as cross-site scripting.

For important sites IMPORTANT high EFFORT

Email Security Overview

STARTTLS

All hosts that receive email need encryption to ensure confidentiality of email messages. Email servers thus need to support STARTTLS, as well as provide decent TLS configuration and correct certificates.

For all sites VERY IMPORTANT low EFFORT

SPF

Sender Policy Framework (SPF) enables organizations to designate servers that are allowed to send email messages on their behalf. With SPF in place, spam is easier to identify.

For important sites IMPORTANT low EFFORT

DMARC

Domain-based Message Authentication, Reporting, and Conformance (DMARC) is a mechanism that allows organizations to specify how unauthenticated email (identified using SPF and DKIM) should be handled.

For important sites IMPORTANT low EFFORT

DNS Zone

The global DNS infrastructure is organized as a series of hierarchical DNS zones. The root zone hosts a number of global and country TLDs, which in turn host further zones that are delegated to their customers. Each organization that controls a zone can delegate parts of its namespace to other zones. In this test we perform detailed inspection of a DNS zone, but only if the host being tested matches the zone.

Test passed

Everything seems to be well configured. Well done.

Nameserver Names

Nameservers can be referred to by name and by address. In this section we show the names, which can appear in the NS records, the referrals from the parent zone, and the SOA record. In some situations, servers from the parent zone respond authoritatively, in which case we will include them in the list as well.

Nameserver	Operational	IPv4	IPv6	Sources
ns1.protonmail.com. PRIMARY 185.70.42.150				NS SOA REFERRAL
ns2.protonmail.com. 176.119.200.150				NS REFERRAL
ns3.protonmail.com. 205.132.47.1				NS REFERRAL

Nameserver Addresses

This section shows the configuration of all discovered nameservers by their IP address. To find all applicable nameservers, we inspect the parent zone nameservers for names and glue and then the tested zone nameservers for NS records. We then resolve all discovered names to IP addresses. Finally, we test each address individually.

Nameserver	Sources	Payload Size
176.119.200.150 ns2.protonmail.com. PTR: 176-119-200-150.protonmail.ch.	NAME, GLUE	1232
185.70.42.150 PRIMARY ns1.protonmail.com. PTR: 185-70-42-150.protonmail.ch.	NAME, GLUE	1232
205.132.47.1 ns3.protonmail.com. PTR: ns3.protonmail.ch.	NAME, GLUE	1232

Start of Authority (SOA) Record

Start of Authority (SOA) records contain administrative information pertaining to one DNS zone, especially the configuration that's used for zone transfers between the primary nameserver and the secondaries. Only one SOA record should exist, with all nameservers providing the same information.

The domain name of the primary nameserver for the zone. Also known as MNAME.Primary nameserver	ns1.protonmail.com.
Email address of the persons responsible for this zone. Also known as RNAME.Admin email	support.protonmail.ch.
Zone serial or version number.Serial number	-1883866146
The length of time secondary nameservers should wait before querying the primary for changes.Refresh interval	1,200 seconds (about 20 minutes)
The length of time secondary nameservers should wait before querying an unresponsive primary again.Retry interval	144 seconds (about 2 minutes)
The length of time after which secondary nameservers should stop responding to queries for a zone, assuming no updates were obtained from the primary.Expire interval	1,814,400 seconds (about 21 days)
TTL for purposes of negative response caching. Negative cache TTL	7,200 seconds (about 2 hours)
Time To Live (TTL) indicates for how long a record remains valid. SOA record TTL	1,200 seconds (about 20 minutes)

Analysis

Nameserver A and AAAA records should have matching reverse records

According to RFC 1912, nameserver's PTR records must match their A and AAAA records to ensure maximum interoperability.

Improve IPv6 support

The Internet is in a slow transition to supporting IPv6 widely. Although at this time it is expected that most recursive DNS servers will use IPv4, adding support for IPv6 will enable transition to networks that use IPv6 exclusively.

No problems detected with the zone configuration

Excellent. This DNS zone is in a good working order. No problems detected.

Backing DNS Queries

Below are all DNS queries we submitted during the zone inspection.

	ID	Server	Transport	Question Name	Type	Status

DNS Records

Correctly functioning name servers are necessary to hold and distribute information that's necessary for your domain name to operate correctly. Examples include converting names to IP addresses, determining where email should go, and so on. More recently, the DNS is being used to communicate email and other security policies.

Test passed

Everything seems to be well configured. Well done.

DNS Records

These are the results of individual DNS queries against your nameserver for common resource record types.

Name	TTL	Type	Data
protonmail.com.	1200	A	185.70.42.12
www.protonmail.com.	1200	A	185.70.42.31
protonmail.com.	1200	CAA	0 iodef "mailto:security@proton.me"
protonmail.com.	1200	CAA	0 issue "digicert.com"
protonmail.com.	1200	CAA	0 issue "sectigo.com"
protonmail.com.	1200	CAA	0 issue "letsencrypt.org"
protonmail.com.	1200	DNSKEY	257 3 13 VRvrqp0hFPeZdrFLfO9f/rtqZg/mlxCAgqkIeeGkTuAmCRLciJv995/2aU1cvGDuKEMVuH23v8OdgqkqqtLIYA==
protonmail.com.	1200	DNSKEY	256 3 13 a99hiIsSCxd/tXoMy1N5A0bqStx2ULvlBQ8KNOiBITu7cMsjjaMOKz7+Ww3dKvc7U/HepwLRAml9AOTueCa1mA==
protonmail.com.	1200	MX	5 mail.protonmail.ch.
protonmail.com.	1200	MX	10 mailsec.protonmail.ch.
protonmail.com.	1159	NS	ns1.protonmail.com.
protonmail.com.	1159	NS	ns2.protonmail.com.
protonmail.com.	1159	NS	ns3.protonmail.com.
protonmail.com.	1200	SOA	ns1.protonmail.com. support.protonmail.ch. 2411101150 1200 144 1814400 7200
protonmail.com.	1200	TXT	"google-site-verification=RVUCKIFDkg-Spau8kEohQRsgyHEBUQcVehZqF6PAQcQ"
protonmail.com.	1200	TXT	"ahrefs-site-verification_4bdac6bbaa81e0d591d7c0f3ef238905c0521b69bf3d74e64d3775bcb2743afd"
protonmail.com.	1200	TXT	"v=spf1 include:_spf.protonmail.ch ~all"
protonmail.com.	1200	TXT	"brave-ledger-verification=66a7f27fb99949cc0c564ab98efcc58ea1bac3e97eb557c782ab2d44b49aefd7"
protonmail.com.	1200	TXT	"yandex-verification: 6059b187e78de544"
protonmail.com.	1200	TXT	"mailru-verification: 14505c6eb222c847"
protonmail.com.	1200	TXT	"google-site-verification=uXVNQLivTppnZssXHtMY7QVn70Mpd0x2U8pKj324Krk"
protonmail.com.	1200	TXT	"google-site-verification=aq9zJnp3H3bNE0Y4D4rH5I5Dhj8VMaLYx0uQ7Rozfgg"
_dmarc.protonmail.com.	1200	TXT	"v=DMARC1; p=quarantine; fo=1; aspf=s; adkim=s;"
_mta-sts.protonmail.com.	1200	CNAME	_mta-sts.protonmail.ch.
_mta-sts.protonmail.ch.	1200	TXT	"v=STSv1; id=190906205100Z;"
_smtp._tls.protonmail.com.	1200	CNAME	_smtp._tls.protonmail.ch.
_smtp._tls.protonmail.ch.	1200	TXT	"v=TLSRPTv1; rua=https://reports.proton.me/reports/smtptls"

Backing DNS Queries

Below are all DNS queries we submitted while inspecting the resource records.

	ID	Server	Question Name	Type	Status

DNSSEC

DNSSEC is an extension of the DNS protocol that provides cryptographic assurance of the authenticity and integrity of responses; it's intended as a defense against network attackers who are able to manipulate DNS to redirect their victims to servers of their choice. DNSSEC is controversial, with the industry split largely between those who think it's essential and those who believe that it's problematic and unnecessary.

Test passed

Everything seems to be well configured. Well done.

Analysis

DNSSEC is well configured

Good. This domain name has well-configured DNSSEC.

Useful DNSSEC Tools

Certification Authority Authorization

CAA (RFC 8659) is a new standard that allows domain name owners to restrict which CAs are allowed to issue certificates for their domains. This can help to reduce the chance of misissuance, either accidentally or maliciously. In September 2017, CAA became mandatory for CAs to implement.

Test passed

Everything seems to be well configured. Well done.

CAA Policy Information

The DNS hostname where this policy is located.Policy host	protonmail.com
The iodef property specifies a means of reporting certificate issue requests or cases of certificate issue for the corresponding domain that violate the security policy of the issuer or the domain name holder.iodef	mailto:security@proton.me flags: 0
The issue property tag is used to request that certificate issuers perform CAA issue restriction processing for the domain and to grant authorization to specific certificate issuers.issue	sectigo.com flags: 0
The issue property tag is used to request that certificate issuers perform CAA issue restriction processing for the domain and to grant authorization to specific certificate issuers.issue	letsencrypt.org flags: 0
The issue property tag is used to request that certificate issuers perform CAA issue restriction processing for the domain and to grant authorization to specific certificate issuers.issue	digicert.com flags: 0

Analysis

Issuance of S/MIME certificates not restricted

This policy doesn't restrict the issuance of S/MIME certificates. Consider using the `issuemail` directive to restrict which CAs, if any, can issue.

Issuance of BIMI not restricted

This policy doesn't restrict issuance of BIMI certificates. Consider using the `issuevmc` directive to restrict which CAs, if any, can issue.

CAA policy restricts issuance

Great. This domain name uses CAA to restrict which CAs are allowed to issue certificates for it.

Policy uses reporting

Good. This policy uses reporting, which means that your contact information is available should someone need to contact you about a CAA violation. Do note that you're not guaranteed to be notified, given that CAs generally don't support notifications yet.

Email (SMTP)

An internet hostname can be served by zero or more mail servers, as specified by MX (mail exchange) DNS resource records. Each server can further resolve to multiple IP addresses, for example to handle IPv4 and IPv6 clients. Thus, in practice, hosts that wish to receive email reliably are supported by many endpoint.

Test passed

Everything seems to be well configured. Well done.

Some TLS and PKI information shown may have been retrieved from cache. The notes provide more information.

Server	Preference	Operational	STARTTLS	TLS	PKI	DNSSEC	DANE
mail.protonmail.ch 185.70.42.128 PTR: mail.protonmail.ch	5
mail.protonmail.ch 176.119.200.128 PTR: mail.protonmail.ch	5
mail.protonmail.ch 185.205.70.128 PTR: mail.protonmail.ch	5
mailsec.protonmail.ch 185.205.70.129 PTR: mailsec.protonmail.ch	10
mailsec.protonmail.ch 185.70.42.129 PTR: mailsec.protonmail.ch	10
mailsec.protonmail.ch 176.119.200.129 PTR: mailsec.protonmail.ch	10

Analysis

Email servers match MTA-STS policy

Good. This host supports MTA-STS, which means that it restricts which MX servers can be used and how they are configured. We've verified that all MX servers listed here match the policy.

Some SMTP server assessments have been retrieved from cache

Some SMTP server assessment results have been retrieved from our cache. Because many hosts point to the same SMTP servers, we use a short-term cache to avoid testing the same SMTP servers over and over again.

Latest cache timestamp: 23 Dec 2024 13:04 UTC

Earliest cache timestamp: 23 Dec 2024 13:04 UTC

Some SMTP server assessments contain partial information

Comprehensive TLS assessments require many connections, which is exactly what many SMTP servers don't like. We implement a two-tier assessment approach. To give you some results as fast as possible, we perform shallow assessments that use only one connection per SMTP server. We then have a background process that performs complete assessments slowly, trying to accommodate each server individually. The results presented here contain partial information. If you come back later we may be able to provide complete assessment resuls.

Email TLS (SMTP)

Transport Layer Security (TLS) is the most widely used encryption protocol on the Internet. In combination with valid certificates, servers can establish trusted communication channels even with users who have never visited them before. Network attackers can't uncover what is being communicated, even when they can see all the traffic.

Test passed

Everything seems to be well configured. Well done.

Some TLS and PKI information shown may have been retrieved from cache. The notes provide more information.

TLS Configuration: mail.protonmail.ch (185.70.42.128) Cached

Encryption protocol version determines what features are available for negotiation between client and server.Supported protocols	TLS v1.2
Shows cipher suite configuration for this protocol version.TLS v1.2	Suite: TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 Suite ID: 0xc030 Cipher name: AES Cipher strength: 256 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: ECDHE_RSA Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA384 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 256 bits (ECDHE 256 bits)
These results have been retrieved from our cache. This row indicates when was that the original test ran.Retrieved from cache	23 Dec 2024 13:04 UTC

Analysis

TLS 1.2 supported

Good. This server supports TLS 1.2, which can provide strong security when configured correctly. This version of the TLS protocol is necessary to provide good security with a wide range of clients that don't yet support TLS 1.3.

Strong key exchange detected

Excellent. All cipher suites on this server rely on strong key exchange. The sweet spot is 2048 bits for DHE and 256 bits for ECDHE. Putting ECDHE suites first guarantees best security and best performance.

Partial results shown

SMTP assessments usually take a long time. To get you some results faster, we initially perform shallow checks. If you come back later we may be able to show you complete results.

Relaxed TLS assessment criteria applied to SMTP on port 25

We apply relaxed assessment criteria when evaluating TLS configuration of SMTP servers on port 25. This is because most delivery agents fall back to delivering via plaintext on failure to negotiate encryption. Some configuration elements that can be abused to attack other ports and protocols (e.g., SSLv2 and export cipher suites) are penalized in the same way as for other protocols. We will review this policy in the future.

TLS Configuration: mail.protonmail.ch (176.119.200.128) Cached

Encryption protocol version determines what features are available for negotiation between client and server.Supported protocols	TLS v1.2
Shows cipher suite configuration for this protocol version.TLS v1.2	Suite: TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 Suite ID: 0xc030 Cipher name: AES Cipher strength: 256 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: ECDHE_RSA Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA384 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 256 bits (ECDHE 256 bits)
These results have been retrieved from our cache. This row indicates when was that the original test ran.Retrieved from cache	23 Dec 2024 13:04 UTC

Analysis

TLS 1.2 supported

Good. This server supports TLS 1.2, which can provide strong security when configured correctly. This version of the TLS protocol is necessary to provide good security with a wide range of clients that don't yet support TLS 1.3.

Strong key exchange detected

Excellent. All cipher suites on this server rely on strong key exchange. The sweet spot is 2048 bits for DHE and 256 bits for ECDHE. Putting ECDHE suites first guarantees best security and best performance.

Partial results shown

SMTP assessments usually take a long time. To get you some results faster, we initially perform shallow checks. If you come back later we may be able to show you complete results.

Relaxed TLS assessment criteria applied to SMTP on port 25

We apply relaxed assessment criteria when evaluating TLS configuration of SMTP servers on port 25. This is because most delivery agents fall back to delivering via plaintext on failure to negotiate encryption. Some configuration elements that can be abused to attack other ports and protocols (e.g., SSLv2 and export cipher suites) are penalized in the same way as for other protocols. We will review this policy in the future.

TLS Configuration: mail.protonmail.ch (185.205.70.128) Cached

Encryption protocol version determines what features are available for negotiation between client and server.Supported protocols	TLS v1.2
Shows cipher suite configuration for this protocol version.TLS v1.2	Suite: TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 Suite ID: 0xc030 Cipher name: AES Cipher strength: 256 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: ECDHE_RSA Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA384 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 256 bits (ECDHE 256 bits)
These results have been retrieved from our cache. This row indicates when was that the original test ran.Retrieved from cache	23 Dec 2024 13:04 UTC

Analysis

TLS 1.2 supported

Good. This server supports TLS 1.2, which can provide strong security when configured correctly. This version of the TLS protocol is necessary to provide good security with a wide range of clients that don't yet support TLS 1.3.

Strong key exchange detected

Excellent. All cipher suites on this server rely on strong key exchange. The sweet spot is 2048 bits for DHE and 256 bits for ECDHE. Putting ECDHE suites first guarantees best security and best performance.

Partial results shown

SMTP assessments usually take a long time. To get you some results faster, we initially perform shallow checks. If you come back later we may be able to show you complete results.

Relaxed TLS assessment criteria applied to SMTP on port 25

We apply relaxed assessment criteria when evaluating TLS configuration of SMTP servers on port 25. This is because most delivery agents fall back to delivering via plaintext on failure to negotiate encryption. Some configuration elements that can be abused to attack other ports and protocols (e.g., SSLv2 and export cipher suites) are penalized in the same way as for other protocols. We will review this policy in the future.

TLS Configuration: mailsec.protonmail.ch (185.205.70.129) Cached

Encryption protocol version determines what features are available for negotiation between client and server.Supported protocols	TLS v1.2
Shows cipher suite configuration for this protocol version.TLS v1.2	Suite: TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 Suite ID: 0xc030 Cipher name: AES Cipher strength: 256 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: ECDHE_RSA Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA384 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 256 bits (ECDHE 256 bits)
These results have been retrieved from our cache. This row indicates when was that the original test ran.Retrieved from cache	23 Dec 2024 13:04 UTC

Analysis

TLS 1.2 supported

Good. This server supports TLS 1.2, which can provide strong security when configured correctly. This version of the TLS protocol is necessary to provide good security with a wide range of clients that don't yet support TLS 1.3.

Strong key exchange detected

Excellent. All cipher suites on this server rely on strong key exchange. The sweet spot is 2048 bits for DHE and 256 bits for ECDHE. Putting ECDHE suites first guarantees best security and best performance.

Partial results shown

SMTP assessments usually take a long time. To get you some results faster, we initially perform shallow checks. If you come back later we may be able to show you complete results.

Relaxed TLS assessment criteria applied to SMTP on port 25

We apply relaxed assessment criteria when evaluating TLS configuration of SMTP servers on port 25. This is because most delivery agents fall back to delivering via plaintext on failure to negotiate encryption. Some configuration elements that can be abused to attack other ports and protocols (e.g., SSLv2 and export cipher suites) are penalized in the same way as for other protocols. We will review this policy in the future.

TLS Configuration: mailsec.protonmail.ch (185.70.42.129) Cached

Encryption protocol version determines what features are available for negotiation between client and server.Supported protocols	TLS v1.2
Shows cipher suite configuration for this protocol version.TLS v1.2	Suite: TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 Suite ID: 0xc030 Cipher name: AES Cipher strength: 256 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: ECDHE_RSA Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA384 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 256 bits (ECDHE 256 bits)
These results have been retrieved from our cache. This row indicates when was that the original test ran.Retrieved from cache	23 Dec 2024 13:04 UTC

Analysis

TLS 1.2 supported

Good. This server supports TLS 1.2, which can provide strong security when configured correctly. This version of the TLS protocol is necessary to provide good security with a wide range of clients that don't yet support TLS 1.3.

Strong key exchange detected

Excellent. All cipher suites on this server rely on strong key exchange. The sweet spot is 2048 bits for DHE and 256 bits for ECDHE. Putting ECDHE suites first guarantees best security and best performance.

Partial results shown

SMTP assessments usually take a long time. To get you some results faster, we initially perform shallow checks. If you come back later we may be able to show you complete results.

Relaxed TLS assessment criteria applied to SMTP on port 25

We apply relaxed assessment criteria when evaluating TLS configuration of SMTP servers on port 25. This is because most delivery agents fall back to delivering via plaintext on failure to negotiate encryption. Some configuration elements that can be abused to attack other ports and protocols (e.g., SSLv2 and export cipher suites) are penalized in the same way as for other protocols. We will review this policy in the future.

TLS Configuration: mailsec.protonmail.ch (176.119.200.129) Cached

Encryption protocol version determines what features are available for negotiation between client and server.Supported protocols	TLS v1.2
Shows cipher suite configuration for this protocol version.TLS v1.2	Suite: TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 Suite ID: 0xc030 Cipher name: AES Cipher strength: 256 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: ECDHE_RSA Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA384 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 256 bits (ECDHE 256 bits)
These results have been retrieved from our cache. This row indicates when was that the original test ran.Retrieved from cache	23 Dec 2024 13:04 UTC

Analysis

TLS 1.2 supported

Good. This server supports TLS 1.2, which can provide strong security when configured correctly. This version of the TLS protocol is necessary to provide good security with a wide range of clients that don't yet support TLS 1.3.

Strong key exchange detected

Excellent. All cipher suites on this server rely on strong key exchange. The sweet spot is 2048 bits for DHE and 256 bits for ECDHE. Putting ECDHE suites first guarantees best security and best performance.

Partial results shown

SMTP assessments usually take a long time. To get you some results faster, we initially perform shallow checks. If you come back later we may be able to show you complete results.

Relaxed TLS assessment criteria applied to SMTP on port 25

We apply relaxed assessment criteria when evaluating TLS configuration of SMTP servers on port 25. This is because most delivery agents fall back to delivering via plaintext on failure to negotiate encryption. Some configuration elements that can be abused to attack other ports and protocols (e.g., SSLv2 and export cipher suites) are penalized in the same way as for other protocols. We will review this policy in the future.

Email Certificates (SMTP)

A certificate is a digital document that contains a public key, some information about the entity associated with it, and a digital signature from the certificate issuer. It’s a mechanism that enables us to exchange, store, and use public keys. Being able to reliably verify the identity of a remote server is crucial in order to achieve secure encrypted communication.

Test passed

Everything seems to be well configured. Well done.

Some TLS and PKI information shown may have been retrieved from cache. The notes provide more information.

Certificate #1 Cached

Leaf certificate

protonmail.com
Issuer: Let's Encrypt
Not Before: 28 Oct 2024 13:13:50 UTC
Not After: 26 Jan 2025 13:13:49 UTC (expires in 1 month 3 days)
Key: RSA 4096 bits
Signature: SHA256withRSA
View details

Names	.pm.me .protonmail.ch .protonmail.com .protonvpn.ch *.protonvpn.com protonmail.com
Subject DN	CN=protonmail.com
Subject Key Identifier	f1a20aff29eff87884e8070ce0568a7664d22ba5
Serial	3a68b730d5aca1cb68732c53cd6dd48dfdc
Not Before	28 Oct 2024 13:13:50 UTC
Not After	26 Jan 2025 13:13:49 UTC
Validity period	90 days
Key Usage	digitalSignature, keyEncipherment
Extended Key Usage	serverAuth, clientAuth
Must Staple	No
Issuer
Issuer DN	CN=R10, O=Let's Encrypt, C=US
Certification Authority	Let's Encrypt
Validation Type	Domain Validation (DV)
Authority Key Identifier	keyid:bbbcc347a5e4bca9c6c3a4720c108da235e1c8e8
Parent Certificate	http://r10.i.lencr.org/
OCSP	http://r10.o.lencr.org
Certificate Transparency
Signed Certificate Timestamps	28 Oct 2024 14:12:20 UTC \| Sectigo 'Mammoth2025h1' \| Qualified 28 Oct 2024 14:12:22 UTC \| Let's Encrypt 'Oak2025h1' \| Qualified
Fingerprints
SHA1	55cbfd0de696c7aa9c1cf1e2d2d28c51c5a133b7
SHA256	36a7e845d65053b3e61b70bdcc439bef149bf05425d61ea21ac7386ced1fa23b
SPKI SHA256	76bb66711da416433ca890a5b2e5a0533c6006478f7d10a4469a947acc8399e1

Analysis

Strong private key

Good. The private key associated with this certificate is secure.

Strong signature algorithm

Good. This certificate uses a strong signature algorithm.

Certificate matches hostname

Good. The provided certificate matches the expected hostnames.

Certificate dates match

Good. The certificate is valid for use at this point of time.

Certificate has not been revoked

Good. This certificate has not been revoked.

Certificate satisfies Apple's CT compliance requirements

Good. This certificate satisfies Apple's CT requirements at present.

Certificate Chain

Leaf certificate

protonmail.com | 36a7e84
Not After: 26 Jan 2025 13:13:49 UTC (expires in 1 month 3 days)
Authentication: RSA 4096 bits (SHA256withRSA)
View details

Names	.pm.me .protonmail.ch .protonmail.com .protonvpn.ch *.protonvpn.com protonmail.com
Subject DN	CN=protonmail.com
Subject Key Identifier	f1a20aff29eff87884e8070ce0568a7664d22ba5
Serial	3a68b730d5aca1cb68732c53cd6dd48dfdc
Not Before	28 Oct 2024 13:13:50 UTC
Not After	26 Jan 2025 13:13:49 UTC
Validity period	90 days
Key Usage	digitalSignature, keyEncipherment
Extended Key Usage	serverAuth, clientAuth
Must Staple	No
Issuer
Issuer DN	CN=R10, O=Let's Encrypt, C=US
Certification Authority	Let's Encrypt
Validation Type	Domain Validation (DV)
Authority Key Identifier	keyid:bbbcc347a5e4bca9c6c3a4720c108da235e1c8e8
Parent Certificate	http://r10.i.lencr.org/
OCSP	http://r10.o.lencr.org
Certificate Transparency
Signed Certificate Timestamps	28 Oct 2024 14:12:20 UTC \| Sectigo 'Mammoth2025h1' \| Qualified 28 Oct 2024 14:12:22 UTC \| Let's Encrypt 'Oak2025h1' \| Qualified
Fingerprints
SHA1	55cbfd0de696c7aa9c1cf1e2d2d28c51c5a133b7
SHA256	36a7e845d65053b3e61b70bdcc439bef149bf05425d61ea21ac7386ced1fa23b
SPKI SHA256	76bb66711da416433ca890a5b2e5a0533c6006478f7d10a4469a947acc8399e1

Intermediate certificate

R10 | 9d7c3f1
Not After: 12 Mar 2027 23:59:59 UTC (expires in 2 years 2 months)
Authentication: RSA 2048 bits (SHA256withRSA)
View details

Subject DN	CN=R10, O=Let's Encrypt, C=US
Subject Key Identifier	bbbcc347a5e4bca9c6c3a4720c108da235e1c8e8
Serial	4ba85293f79a2fa273064ba8048d75d0
Not Before	13 Mar 2024 00:00:00 UTC
Not After	12 Mar 2027 23:59:59 UTC
Validity period	1095 days
Key Usage	digitalSignature, keyCertSign, cRLSign
Extended Key Usage	clientAuth, serverAuth
Issuer
Issuer DN	CN=ISRG Root X1, O=Internet Security Research Group, C=US
Certification Authority	Let's Encrypt
Validation Type	Not Applicable
Authority Key Identifier	keyid:79b459e67bb6e5e40173800888c81a58f6e99b6e
Parent Certificate	http://x1.i.lencr.org/
CRL	http://x1.c.lencr.org/
CA certificate	Yes (pathlen 0)
Fingerprints
SHA1	00abefd055f9a9c784ffdeabd1dcdd8fed741436
SHA256	9d7c3f1aa6ad2b2ec0d5cf1e246f8d9ae6cbc9fd0755ad37bb974b1f2fb603f3
SPKI SHA256	2bbad93ab5c79279ec121507f272cbe0c6647a3aae52e22f388afab426b4adba

Root certificate

ISRG Root X1 | 96bcec0
Not After: 04 Jun 2035 11:04:38 UTC (expires in 10 years 5 months)
Authentication: RSA 4096 bits (SHA256withRSA)
View details

Subject DN	CN=ISRG Root X1, O=Internet Security Research Group, C=US
Subject Key Identifier	79b459e67bb6e5e40173800888c81a58f6e99b6e
Serial	8210cfb0d240e3594463e0bb63828b00
Not Before	04 Jun 2015 11:04:38 UTC
Not After	04 Jun 2035 11:04:38 UTC
Key Usage	keyCertSign, cRLSign
Issuer
Issuer DN	CN=ISRG Root X1, O=Internet Security Research Group, C=US
Certification Authority	Let's Encrypt
Validation Type	Self-signed
CA certificate	Yes (pathlen unlimited)
Fingerprints
SHA1	cabd2a79a1076a31f21d253635cb039d4329a5e8
SHA256	96bcec06264976f37460779acf28c5a7cfe8a3c0aae11a8ffcee05c0bddf08c6
SPKI SHA256	0b9fa5a59eed715c26c1020c711b4f6ec42d58b0015e14337a39dad301c5afc3

Analysis

Certificate chain is correct

Good. This chain contains all the right certificates and in the right order.

Email DANE (SMTP)

DNS-based Authentication of Named Entities (DANE) is a bridge between DNSSEC and TLS. In one possible scenario, DANE can be used for public key pinning, building on an existing publicly-trusted certificate. In another approach, it can be used to completely bypass the CA ecosystem and establish trust using DNSSEC alone.

Test passed

Everything seems to be well configured. Well done.

Some TLS and PKI information shown may have been retrieved from cache. The notes provide more information.

DANE: mail.protonmail.ch (185.70.42.128)

Specifies which certificate in the chain is being pinned and how validation should be performed.Certificate Usage	Domain-issued certificate / DANE-EE (3)
Determines if the association is made with a certificate or with a public key (via its SPKI structure).Selector	SPKI structure (1)
Determines how matching is done; directly or via a hash. Matching Type	SHA2-256 (1)
Contains the data necessary to perform the matching. Data	6111a5698d23c89e09c36ff833c1487edc1b0c841f87c49dae8f7a09e11e979e

Specifies which certificate in the chain is being pinned and how validation should be performed.Certificate Usage	Domain-issued certificate / DANE-EE (3)
Determines if the association is made with a certificate or with a public key (via its SPKI structure).Selector	SPKI structure (1)
Determines how matching is done; directly or via a hash. Matching Type	SHA2-256 (1)
Contains the data necessary to perform the matching. Data	76bb66711da416433ca890a5b2e5a0533c6006478f7d10a4469a947acc8399e1 Leaf certificate: RSA 4096 bits Subject: CN=protonmail.com Issuer: CN=R10, O=Let's Encrypt, C=US protonmail.com (RSA 4096 bits)

Analysis

Valid DANE configuration

Excellent. Your DANE configuration matches the certificate chain(s) provided by the service. Your TLS configuration enjoys the additional benefit of DANE validation.

DANE: mail.protonmail.ch (176.119.200.128)

Specifies which certificate in the chain is being pinned and how validation should be performed.Certificate Usage	Domain-issued certificate / DANE-EE (3)
Determines if the association is made with a certificate or with a public key (via its SPKI structure).Selector	SPKI structure (1)
Determines how matching is done; directly or via a hash. Matching Type	SHA2-256 (1)
Contains the data necessary to perform the matching. Data	6111a5698d23c89e09c36ff833c1487edc1b0c841f87c49dae8f7a09e11e979e

Specifies which certificate in the chain is being pinned and how validation should be performed.Certificate Usage	Domain-issued certificate / DANE-EE (3)
Determines if the association is made with a certificate or with a public key (via its SPKI structure).Selector	SPKI structure (1)
Determines how matching is done; directly or via a hash. Matching Type	SHA2-256 (1)
Contains the data necessary to perform the matching. Data	76bb66711da416433ca890a5b2e5a0533c6006478f7d10a4469a947acc8399e1 Leaf certificate: RSA 4096 bits Subject: CN=protonmail.com Issuer: CN=R10, O=Let's Encrypt, C=US protonmail.com (RSA 4096 bits)

Analysis

Valid DANE configuration

Excellent. Your DANE configuration matches the certificate chain(s) provided by the service. Your TLS configuration enjoys the additional benefit of DANE validation.

DANE: mail.protonmail.ch (185.205.70.128)

Specifies which certificate in the chain is being pinned and how validation should be performed.Certificate Usage	Domain-issued certificate / DANE-EE (3)
Determines if the association is made with a certificate or with a public key (via its SPKI structure).Selector	SPKI structure (1)
Determines how matching is done; directly or via a hash. Matching Type	SHA2-256 (1)
Contains the data necessary to perform the matching. Data	6111a5698d23c89e09c36ff833c1487edc1b0c841f87c49dae8f7a09e11e979e

Specifies which certificate in the chain is being pinned and how validation should be performed.Certificate Usage	Domain-issued certificate / DANE-EE (3)
Determines if the association is made with a certificate or with a public key (via its SPKI structure).Selector	SPKI structure (1)
Determines how matching is done; directly or via a hash. Matching Type	SHA2-256 (1)
Contains the data necessary to perform the matching. Data	76bb66711da416433ca890a5b2e5a0533c6006478f7d10a4469a947acc8399e1 Leaf certificate: RSA 4096 bits Subject: CN=protonmail.com Issuer: CN=R10, O=Let's Encrypt, C=US protonmail.com (RSA 4096 bits)

Analysis

Valid DANE configuration

Excellent. Your DANE configuration matches the certificate chain(s) provided by the service. Your TLS configuration enjoys the additional benefit of DANE validation.

DANE: mailsec.protonmail.ch (185.205.70.129)

Specifies which certificate in the chain is being pinned and how validation should be performed.Certificate Usage	Domain-issued certificate / DANE-EE (3)
Determines if the association is made with a certificate or with a public key (via its SPKI structure).Selector	SPKI structure (1)
Determines how matching is done; directly or via a hash. Matching Type	SHA2-256 (1)
Contains the data necessary to perform the matching. Data	6111a5698d23c89e09c36ff833c1487edc1b0c841f87c49dae8f7a09e11e979e

Specifies which certificate in the chain is being pinned and how validation should be performed.Certificate Usage	Domain-issued certificate / DANE-EE (3)
Determines if the association is made with a certificate or with a public key (via its SPKI structure).Selector	SPKI structure (1)
Determines how matching is done; directly or via a hash. Matching Type	SHA2-256 (1)
Contains the data necessary to perform the matching. Data	76bb66711da416433ca890a5b2e5a0533c6006478f7d10a4469a947acc8399e1 Leaf certificate: RSA 4096 bits Subject: CN=protonmail.com Issuer: CN=R10, O=Let's Encrypt, C=US protonmail.com (RSA 4096 bits)

Analysis

Valid DANE configuration

Excellent. Your DANE configuration matches the certificate chain(s) provided by the service. Your TLS configuration enjoys the additional benefit of DANE validation.

DANE: mailsec.protonmail.ch (185.70.42.129)

Specifies which certificate in the chain is being pinned and how validation should be performed.Certificate Usage	Domain-issued certificate / DANE-EE (3)
Determines if the association is made with a certificate or with a public key (via its SPKI structure).Selector	SPKI structure (1)
Determines how matching is done; directly or via a hash. Matching Type	SHA2-256 (1)
Contains the data necessary to perform the matching. Data	6111a5698d23c89e09c36ff833c1487edc1b0c841f87c49dae8f7a09e11e979e

Specifies which certificate in the chain is being pinned and how validation should be performed.Certificate Usage	Domain-issued certificate / DANE-EE (3)
Determines if the association is made with a certificate or with a public key (via its SPKI structure).Selector	SPKI structure (1)
Determines how matching is done; directly or via a hash. Matching Type	SHA2-256 (1)
Contains the data necessary to perform the matching. Data	76bb66711da416433ca890a5b2e5a0533c6006478f7d10a4469a947acc8399e1 Leaf certificate: RSA 4096 bits Subject: CN=protonmail.com Issuer: CN=R10, O=Let's Encrypt, C=US protonmail.com (RSA 4096 bits)

Analysis

Valid DANE configuration

Excellent. Your DANE configuration matches the certificate chain(s) provided by the service. Your TLS configuration enjoys the additional benefit of DANE validation.

DANE: mailsec.protonmail.ch (176.119.200.129)

Specifies which certificate in the chain is being pinned and how validation should be performed.Certificate Usage	Domain-issued certificate / DANE-EE (3)
Determines if the association is made with a certificate or with a public key (via its SPKI structure).Selector	SPKI structure (1)
Determines how matching is done; directly or via a hash. Matching Type	SHA2-256 (1)
Contains the data necessary to perform the matching. Data	6111a5698d23c89e09c36ff833c1487edc1b0c841f87c49dae8f7a09e11e979e

Specifies which certificate in the chain is being pinned and how validation should be performed.Certificate Usage	Domain-issued certificate / DANE-EE (3)
Determines if the association is made with a certificate or with a public key (via its SPKI structure).Selector	SPKI structure (1)
Determines how matching is done; directly or via a hash. Matching Type	SHA2-256 (1)
Contains the data necessary to perform the matching. Data	76bb66711da416433ca890a5b2e5a0533c6006478f7d10a4469a947acc8399e1 Leaf certificate: RSA 4096 bits Subject: CN=protonmail.com Issuer: CN=R10, O=Let's Encrypt, C=US protonmail.com (RSA 4096 bits)

Analysis

Valid DANE configuration

Excellent. Your DANE configuration matches the certificate chain(s) provided by the service. Your TLS configuration enjoys the additional benefit of DANE validation.

SPF

Sender Policy Framework (SPF) is a protocol that allows domain name owners to control which internet hosts are allowed to send email on their behalf. This simple mechanism can be used to reduce the effect of email spoofing and cut down on spam.

Test passed

Everything seems to be well configured. Well done.

SPF Policy Information Main policy

Host where this policy is located.Location	protonmail.com
SPF version used by this policy.v	spf1
Evaluates SPF policy specified in another DNS location. This directive is typically used to allow hosts controlled by another organization. include	_spf.protonmail.ch
This policy element always matches. It's normally used at the end of a policy to specify the handling of hosts that don't match earlier mechanisms. ~all

Analysis

SPF policy found

Policy text: v=spf1 include:_spf.protonmail.ch ~all

Location: protonmail.com

SPF policy is valid

Good. Your SPF policy is syntactically valid.

Policy DNS lookups under limit

Good. Your policy stays under the limit of up to 10 DNS queries. The SPF specification Section 4.6.4. requires implementations to limit the total number of DNS queries. Policies that exceed the limit should not be used and may not work in practice.

Lookups: 2

SPF Policy Information Included policy

Host where this policy is located.Location	_spf.protonmail.ch
SPF version used by this policy.v	spf1
This mechanism tests whether the IP address being tested is contained within a given IPv4 network. ip4	185.70.40.0/24
This mechanism tests whether the IP address being tested is contained within a given IPv4 network. ip4	185.70.41.0/24
This mechanism tests whether the IP address being tested is contained within a given IPv4 network. ip4	185.70.43.0/24
This mechanism tests whether the IP address being tested is contained within a given IPv4 network. ip4	79.135.106.0/24
This mechanism tests whether the IP address being tested is contained within a given IPv4 network. ip4	79.135.107.0/24
Evaluates SPF policy specified in another DNS location. This directive is typically used to allow hosts controlled by another organization. include	_spf2.protonmail.ch
This policy element always matches. It's normally used at the end of a policy to specify the handling of hosts that don't match earlier mechanisms. ~all

SPF Policy Information Included policy

Host where this policy is located.Location	_spf2.protonmail.ch
SPF version used by this policy.v	spf1
This mechanism tests whether the IP address being tested is contained within a given IPv4 network. ip4	51.89.119.103
This mechanism tests whether the IP address being tested is contained within a given IPv4 network. ip4	91.134.188.129
This mechanism tests whether the IP address being tested is contained within a given IPv4 network. ip4	51.77.79.158
This mechanism tests whether the IP address being tested is contained within a given IPv4 network. ip4	54.38.221.122
This mechanism tests whether the IP address being tested is contained within a given IPv4 network. ip4	188.165.51.139
This mechanism tests whether the IP address being tested is contained within a given IPv4 network. ip4	54.36.149.183
This policy element always matches. It's normally used at the end of a policy to specify the handling of hosts that don't match earlier mechanisms. ~all

DMARC

Domain-based Message Authentication, Reporting, and Conformance (DMARC) is a scalable mechanism by which a mail-originating organization can express domain-level policies and preferences for message validation, disposition, and reporting, that a mail-receiving organization can use to improve mail handling.

Test passed

Everything seems to be well configured. Well done.

DMARC Policy Information

The location from which we obtained this policy.Policy location	_dmarc.protonmail.com
DMARC version used by this policy.v	DMARC1
Indicates the policy to be enacted by the receiver at the request of the domain owner. Possible values are: none, quarantine, and reject.p	quarantine
Configures failure reporting.fo	1
Indicates whether strict or relaxed SPF alignment mode is required.aspf	s
Indicates whether strict or relaxed DKIM alignment mode is required.adkim	s

Analysis

DMARC policy found

Policy: v=DMARC1; p=quarantine; fo=1; aspf=s; adkim=s;

Host: _dmarc.protonmail.com

Policy is valid

Good. You have a valid DMARC policy.

MTA Strict Transport Security

SMTP Mail Transfer Agent Strict Transport Security (MTA-STS) is a mechanism enabling mail service providers to declare their ability to receive Transport Layer Security (TLS) secure SMTP connections, and to specify whether sending SMTP servers should refuse to deliver to MX hosts that do not offer TLS with a trusted server certificate.

Test passed

Everything seems to be well configured. Well done.

MTA-STS Policy Indicator

Location from which we retrieved the policy indicator.Location	_mta-sts.protonmail.com
MTA-STS standard version used by this policy indicator.Version	STSv1
Unique policy identifier, whose value must change every time the underlying policy changes.ID	190906205100Z

Analysis

MTA-STS policy indicator valid

Good. Your MTA-STS policy indicator is valid.

MTA-STS Policy

The URL from which the policy was obtained.Location	https://mta-sts.protonmail.com/.well-known/mta-sts.txt
Policy standard version.version	STSv1
Policy duration, which specifies how long the sending MTAs should remember and enforce the server policy for.max‑age	604,800 seconds (about 7 days)
Policy mode, which can be one of 'none', 'testing' and 'enforcing'. Guess which is best! :)mode	enforce
One 'mx' directive specifies one email server pattern that's allowed for this host.mx	mail.protonmail.ch
One 'mx' directive specifies one email server pattern that's allowed for this host.mx	mailsec.protonmail.ch

Analysis

MTA-STS policy is valid

Good. Your MTA-STS policy is valid.

Policy host certificate is valid

Good. Your MTA-STS policy is delivered via a web server that has a valid publicly trusted certificate. This is a necessary condition for the policy to be recognized.

Policy HTTPS response information

Status code: 200

Length: 93 bytes

Content-Type: text/plain; charset=UTF-8

Certificate: mta-sts.protonmail.com

Leaf certificate

protonmail.com
Issuer: Let's Encrypt
Not Before: 22 Dec 2024 13:13:52 UTC
Not After: 22 Mar 2025 13:13:51 UTC (expires in 2 months 27 days)
Key: RSA 4096 bits
Signature: SHA256withRSA
View details

Names	.pm.me .protonmail.ch .protonmail.com .protonvpn.ch *.protonvpn.com protonmail.com
Subject DN	CN=protonmail.com
Subject Key Identifier	f1a20aff29eff87884e8070ce0568a7664d22ba5
Serial	3274d3e58c3cc7af6f2ddadcf2b552be523
Not Before	22 Dec 2024 13:13:52 UTC
Not After	22 Mar 2025 13:13:51 UTC
Validity period	90 days
Key Usage	digitalSignature, keyEncipherment
Extended Key Usage	serverAuth, clientAuth
Must Staple	No
Issuer
Issuer DN	CN=R11, O=Let's Encrypt, C=US
Certification Authority	Let's Encrypt
Validation Type	Domain Validation (DV)
Authority Key Identifier	keyid:c5cf46a4eaf4c3c07a6c95c42db05e922f26e3b9
Parent Certificate	http://r11.i.lencr.org/
OCSP	http://r11.o.lencr.org
Certificate Transparency
Signed Certificate Timestamps	22 Dec 2024 14:12:22 UTC \| Let's Encrypt 'Oak2025h1' \| Qualified 22 Dec 2024 14:12:22 UTC \| Cloudflare 'Nimbus2025' \| Qualified
Fingerprints
SHA1	7b67d685ae0deda4c3fc515f67fb78d48adf7e6e
SHA256	97fea14c8e6cd32ba2221865f535aa52541c8b3a73644fc4fe6ff842864f2a73
SPKI SHA256	76bb66711da416433ca890a5b2e5a0533c6006478f7d10a4469a947acc8399e1

Analysis

Strong private key

Good. The private key associated with this certificate is secure.

Strong signature algorithm

Good. This certificate uses a strong signature algorithm.

Certificate matches hostname

Good. The provided certificate matches the expected hostnames.

Certificate dates match

Good. The certificate is valid for use at this point of time.

Certificate has not been revoked

Good. This certificate has not been revoked.

Certificate satisfies Apple's CT compliance requirements

Good. This certificate satisfies Apple's CT requirements at present.

Certificate Chain

Leaf certificate

protonmail.com | 97fea14 HPKP-RO-PIN
Not After: 22 Mar 2025 13:13:51 UTC (expires in 2 months 27 days)
Authentication: RSA 4096 bits (SHA256withRSA)
View details

Names	.pm.me .protonmail.ch .protonmail.com .protonvpn.ch *.protonvpn.com protonmail.com
Subject DN	CN=protonmail.com
Subject Key Identifier	f1a20aff29eff87884e8070ce0568a7664d22ba5
Serial	3274d3e58c3cc7af6f2ddadcf2b552be523
Not Before	22 Dec 2024 13:13:52 UTC
Not After	22 Mar 2025 13:13:51 UTC
Validity period	90 days
Key Usage	digitalSignature, keyEncipherment
Extended Key Usage	serverAuth, clientAuth
Must Staple	No
Issuer
Issuer DN	CN=R11, O=Let's Encrypt, C=US
Certification Authority	Let's Encrypt
Validation Type	Domain Validation (DV)
Authority Key Identifier	keyid:c5cf46a4eaf4c3c07a6c95c42db05e922f26e3b9
Parent Certificate	http://r11.i.lencr.org/
OCSP	http://r11.o.lencr.org
Certificate Transparency
Signed Certificate Timestamps	22 Dec 2024 14:12:22 UTC \| Let's Encrypt 'Oak2025h1' \| Qualified 22 Dec 2024 14:12:22 UTC \| Cloudflare 'Nimbus2025' \| Qualified
Fingerprints
SHA1	7b67d685ae0deda4c3fc515f67fb78d48adf7e6e
SHA256	97fea14c8e6cd32ba2221865f535aa52541c8b3a73644fc4fe6ff842864f2a73
SPKI SHA256	76bb66711da416433ca890a5b2e5a0533c6006478f7d10a4469a947acc8399e1

Intermediate certificate

R11 | 591e9ce
Not After: 12 Mar 2027 23:59:59 UTC (expires in 2 years 2 months)
Authentication: RSA 2048 bits (SHA256withRSA)
View details

Subject DN	CN=R11, O=Let's Encrypt, C=US
Subject Key Identifier	c5cf46a4eaf4c3c07a6c95c42db05e922f26e3b9
Serial	8a7d3e13d62f30ef2386bd29076b34f8
Not Before	13 Mar 2024 00:00:00 UTC
Not After	12 Mar 2027 23:59:59 UTC
Validity period	1095 days
Key Usage	digitalSignature, keyCertSign, cRLSign
Extended Key Usage	clientAuth, serverAuth
Issuer
Issuer DN	CN=ISRG Root X1, O=Internet Security Research Group, C=US
Certification Authority	Let's Encrypt
Validation Type	Not Applicable
Authority Key Identifier	keyid:79b459e67bb6e5e40173800888c81a58f6e99b6e
Parent Certificate	http://x1.i.lencr.org/
CRL	http://x1.c.lencr.org/
CA certificate	Yes (pathlen 0)
Fingerprints
SHA1	696db3af0dffc17e65c6a20d925c5a7bd24dec7e
SHA256	591e9ce6c863d3a079e9fabe1478c7339a26b21269dde795211361024ae31a44
SPKI SHA256	6ddac18698f7f1f7e1c69b9bce420d974ac6f94ca8b2c761701623f99c767dc7

Root certificate

ISRG Root X1 | 96bcec0
Not After: 04 Jun 2035 11:04:38 UTC (expires in 10 years 5 months)
Authentication: RSA 4096 bits (SHA256withRSA)
View details

Subject DN	CN=ISRG Root X1, O=Internet Security Research Group, C=US
Subject Key Identifier	79b459e67bb6e5e40173800888c81a58f6e99b6e
Serial	8210cfb0d240e3594463e0bb63828b00
Not Before	04 Jun 2015 11:04:38 UTC
Not After	04 Jun 2035 11:04:38 UTC
Key Usage	keyCertSign, cRLSign
Issuer
Issuer DN	CN=ISRG Root X1, O=Internet Security Research Group, C=US
Certification Authority	Let's Encrypt
Validation Type	Self-signed
CA certificate	Yes (pathlen unlimited)
Fingerprints
SHA1	cabd2a79a1076a31f21d253635cb039d4329a5e8
SHA256	96bcec06264976f37460779acf28c5a7cfe8a3c0aae11a8ffcee05c0bddf08c6
SPKI SHA256	0b9fa5a59eed715c26c1020c711b4f6ec42d58b0015e14337a39dad301c5afc3

Analysis

Certificate chain is correct

Good. This chain contains all the right certificates and in the right order.

SMTP TLS Reporting

SMTP TLS Reporting (RFC 8460), or TLS-RPT for short, describes a reporting mechanism and format by which systems sending email can share statistics and specific information about potential failures with recipient domains. Recipient domains can then use this information to both detect potential attacks and diagnose unintentional misconfigurations. TLS-RPT can be used with DANE or MTA-STS.

Test passed

Everything seems to be well configured. Well done.

TLS-RPT Policy

Location from which we retrieved the policy indicator.Location	_smtp._tls.protonmail.com
TLS-RPT standard version used by this policy indicator.Version	TLSRPTv1
Reporting endpoints specified in the policy.Reporting Endpoints	https://reports.proton.me/reports/smtptls

Analysis

SMTP TLS-RPT policy valid

Good. Your TLS-RPT policy is valid. SMTP TLS Reporting is a young standard that is not yet widely supported, but support is probably going to increase over time.

HTTP (80)

To observe your HTTP implementation, we submit a request to the homepage of your site on port 80, follow all redirections (even when they take us to other domain names), and record the returned HTTP headers.

Test passed

Everything seems to be well configured. Well done.

URL: http://protonmail.com/

1

http://protonmail.com/

HTTP/1.1 301 Moved Permanently

content-length	0
location	https://protonmail.com/

2

https://protonmail.com/

HTTP/1.1 301 Moved Permanently

date	Mon, 23 Dec 2024 13:11:10 GMT
set-cookie	Session-Id=Z2lhbm3yw8wXzdRgggIu9QAAAds; Domain=protonmail.com; Path=/; HttpOnly; SameSite=None; Secure; Max-Age=7776000
set-cookie	Tag=redirect; Path=/; SameSite=None; Secure; Max-Age=7776000
cache-control	no-store
location	https://proton.me/mail
content-length	230
content-type	text/html; charset=iso-8859-1
strict-transport-security	max-age=31536000; includeSubDomains; preload
public-key-pins-report-only	pin-sha256="8joiNBdqaYiQpKskgtkJsqRxF7zN0C0aqfi8DacknnI="; pin-sha256="drtmcR2kFkM8qJClsuWgUzxgBkePfRCkRpqUesyDmeE="; report-uri="https://reports.proton.me/reports/tls"
x-frame-options	deny
x-content-type-options	nosniff
x-xss-protection	0
referrer-policy	strict-origin-when-cross-origin
x-permitted-cross-domain-policies	none
onion-location	https://protonmailrmez3lotccipshtkleegetolb73fuirgj7r4o4vfu7ozyd.onion/

3

https://proton.me/mail

HTTP/1.1 200 OK

date	Mon, 23 Dec 2024 13:11:07 GMT
set-cookie	Domain=proton.me; Path=/; HttpOnly; SameSite=None; Secure; Max-Age=7776000
set-cookie	Tag=default; Path=/; SameSite=None; Secure; Max-Age=7776000
last-modified	Thu, 19 Dec 2024 15:04:13 GMT
etag	"35189-629a0d7d79540-gzip"
accept-ranges	bytes
vary	Accept-Encoding
cache-control	public, max-age=1, s-maxage=5, must-revalidate
content-type	text/html; charset=utf-8
age	4
content-security-policy-report-only	default-src 'self'; media-src https://static.zdassets.com; connect-src 'self' wss: https://protonmail.zendesk.com https://ekr.zdassets.com blob: https://account.proton.me https://reports.proton.me https://.algolia.net https://.algolianet.com https://go.getproton.me; script-src 'self' blob: 'unsafe-eval' 'unsafe-inline' https://static.zdassets.com https://pmecdn.protonweb.com; style-src 'self' 'unsafe-inline' https://pmecdn.protonweb.com; font-src 'self' https://pmecdn.protonweb.com; img-src 'self' data: blob: https:; object-src 'self' data: blob:; frame-src 'self' data: blob: https://www.youtube-nocookie.com; child-src 'self' data: blob:; report-uri https://reports.proton.me/reports/csp; frame-ancestors 'self';
strict-transport-security	max-age=31536000; includeSubDomains; preload
public-key-pins-report-only	pin-sha256="CT56BhOTmj5ZIPgb/xD5mH8rY3BLo/MlhP7oPyJUEDo="; pin-sha256="35Dx28/uzN3LeltkCBQ8RHK0tlNSa2kCpCRGNp34Gxc="; report-uri="https://reports.proton.me/reports/tls"
x-frame-options	sameorigin
x-content-type-options	nosniff
x-xss-protection	0
referrer-policy	strict-origin-when-cross-origin
x-permitted-cross-domain-policies	none

Analysis

HTTP redirects to HTTPS

Good. This plaintext HTTP server redirects to HTTPS.

URL: http://www.protonmail.com/

1

http://www.protonmail.com/

HTTP/1.1 301 Moved Permanently

content-length	0
location	https://protonmail.com

2

https://protonmail.com

HTTP/1.1 301 Moved Permanently

date	Mon, 23 Dec 2024 13:11:12 GMT
set-cookie	Session-Id=Z2lhcBeGxbdcUGn4G685jwAAAdw; Domain=protonmail.com; Path=/; HttpOnly; SameSite=None; Secure; Max-Age=7776000
set-cookie	Tag=redirect; Path=/; SameSite=None; Secure; Max-Age=7776000
cache-control	no-store
location	https://proton.me/mail
content-length	230
content-type	text/html; charset=iso-8859-1
strict-transport-security	max-age=31536000; includeSubDomains; preload
public-key-pins-report-only	pin-sha256="8joiNBdqaYiQpKskgtkJsqRxF7zN0C0aqfi8DacknnI="; pin-sha256="drtmcR2kFkM8qJClsuWgUzxgBkePfRCkRpqUesyDmeE="; report-uri="https://reports.proton.me/reports/tls"
x-frame-options	deny
x-content-type-options	nosniff
x-xss-protection	0
referrer-policy	strict-origin-when-cross-origin
x-permitted-cross-domain-policies	none
onion-location	https://protonmailrmez3lotccipshtkleegetolb73fuirgj7r4o4vfu7ozyd.onion/

3

https://proton.me/mail

HTTP/1.1 200 OK

date	Mon, 23 Dec 2024 13:11:12 GMT
set-cookie	Domain=proton.me; Path=/; HttpOnly; SameSite=None; Secure; Max-Age=7776000
set-cookie	Tag=default; Path=/; SameSite=None; Secure; Max-Age=7776000
last-modified	Thu, 19 Dec 2024 15:04:13 GMT
etag	"35189-629a0d7d79540-gzip"
accept-ranges	bytes
vary	Accept-Encoding
cache-control	public, max-age=1, s-maxage=5, must-revalidate
content-type	text/html; charset=utf-8
age	0
content-security-policy-report-only	default-src 'self'; media-src https://static.zdassets.com; connect-src 'self' wss: https://protonmail.zendesk.com https://ekr.zdassets.com blob: https://account.proton.me https://reports.proton.me https://.algolia.net https://.algolianet.com https://go.getproton.me; script-src 'self' blob: 'unsafe-eval' 'unsafe-inline' https://static.zdassets.com https://pmecdn.protonweb.com; style-src 'self' 'unsafe-inline' https://pmecdn.protonweb.com; font-src 'self' https://pmecdn.protonweb.com; img-src 'self' data: blob: https:; object-src 'self' data: blob:; frame-src 'self' data: blob: https://www.youtube-nocookie.com; child-src 'self' data: blob:; report-uri https://reports.proton.me/reports/csp; frame-ancestors 'self';
strict-transport-security	max-age=31536000; includeSubDomains; preload
public-key-pins-report-only	pin-sha256="CT56BhOTmj5ZIPgb/xD5mH8rY3BLo/MlhP7oPyJUEDo="; pin-sha256="35Dx28/uzN3LeltkCBQ8RHK0tlNSa2kCpCRGNp34Gxc="; report-uri="https://reports.proton.me/reports/tls"
x-frame-options	sameorigin
x-content-type-options	nosniff
x-xss-protection	0
referrer-policy	strict-origin-when-cross-origin
x-permitted-cross-domain-policies	none

Analysis

HTTP redirects to HTTPS

Good. This plaintext HTTP server redirects to HTTPS.

HTTP (443)

To observe your HTTPS implementation, we submit a request to the homepage of your site on port 443, follow all redirections (even when they take us to other domain names), and record the returned HTTP headers. We use the most recent set of headers returned from the tested hostname for further tests such as HSTS and HPKP.

Test passed

Everything seems to be well configured. Well done.

URL: https://protonmail.com/

1

https://protonmail.com/

HTTP/1.1 301 Moved Permanently

date	Mon, 23 Dec 2024 13:11:13 GMT
set-cookie	Session-Id=Z2lhcReGxbdcUGn4G685oAAAAcs; Domain=protonmail.com; Path=/; HttpOnly; SameSite=None; Secure; Max-Age=7776000
set-cookie	Tag=redirect; Path=/; SameSite=None; Secure; Max-Age=7776000
cache-control	no-store
location	https://proton.me/mail
content-length	230
content-type	text/html; charset=iso-8859-1
strict-transport-security	max-age=31536000; includeSubDomains; preload
public-key-pins-report-only	pin-sha256="8joiNBdqaYiQpKskgtkJsqRxF7zN0C0aqfi8DacknnI="; pin-sha256="drtmcR2kFkM8qJClsuWgUzxgBkePfRCkRpqUesyDmeE="; report-uri="https://reports.proton.me/reports/tls"
x-frame-options	deny
x-content-type-options	nosniff
x-xss-protection	0
referrer-policy	strict-origin-when-cross-origin
x-permitted-cross-domain-policies	none
onion-location	https://protonmailrmez3lotccipshtkleegetolb73fuirgj7r4o4vfu7ozyd.onion/

2

https://proton.me/mail

HTTP/1.1 200 OK

date	Mon, 23 Dec 2024 13:11:12 GMT
set-cookie	Domain=proton.me; Path=/; HttpOnly; SameSite=None; Secure; Max-Age=7776000
set-cookie	Tag=default; Path=/; SameSite=None; Secure; Max-Age=7776000
last-modified	Thu, 19 Dec 2024 15:04:13 GMT
etag	"35189-629a0d7d79540-gzip"
accept-ranges	bytes
vary	Accept-Encoding
cache-control	public, max-age=1, s-maxage=5, must-revalidate
content-type	text/html; charset=utf-8
age	1
content-security-policy-report-only	default-src 'self'; media-src https://static.zdassets.com; connect-src 'self' wss: https://protonmail.zendesk.com https://ekr.zdassets.com blob: https://account.proton.me https://reports.proton.me https://.algolia.net https://.algolianet.com https://go.getproton.me; script-src 'self' blob: 'unsafe-eval' 'unsafe-inline' https://static.zdassets.com https://pmecdn.protonweb.com; style-src 'self' 'unsafe-inline' https://pmecdn.protonweb.com; font-src 'self' https://pmecdn.protonweb.com; img-src 'self' data: blob: https:; object-src 'self' data: blob:; frame-src 'self' data: blob: https://www.youtube-nocookie.com; child-src 'self' data: blob:; report-uri https://reports.proton.me/reports/csp; frame-ancestors 'self';
strict-transport-security	max-age=31536000; includeSubDomains; preload
public-key-pins-report-only	pin-sha256="CT56BhOTmj5ZIPgb/xD5mH8rY3BLo/MlhP7oPyJUEDo="; pin-sha256="35Dx28/uzN3LeltkCBQ8RHK0tlNSa2kCpCRGNp34Gxc="; report-uri="https://reports.proton.me/reports/tls"
x-frame-options	sameorigin
x-content-type-options	nosniff
x-xss-protection	0
referrer-policy	strict-origin-when-cross-origin
x-permitted-cross-domain-policies	none

URL: https://www.protonmail.com/

1

https://www.protonmail.com/

HTTP/1.1 301 Moved Permanently

content-length	0
location	https://proton.me
strict-transport-security	max-age=31536000; includeSubDomains; preload
public-key-pins-report-only	pin-sha256="8joiNBdqaYiQpKskgtkJsqRxF7zN0C0aqfi8DacknnI="; pin-sha256="drtmcR2kFkM8qJClsuWgUzxgBkePfRCkRpqUesyDmeE="; report-uri="https://reports.proton.me/reports/tls"
x-frame-options	deny
x-content-type-options	nosniff
x-xss-protection	0
referrer-policy	strict-origin-when-cross-origin
x-permitted-cross-domain-policies	none

2

https://proton.me

HTTP/1.1 200 OK

date	Mon, 23 Dec 2024 13:11:14 GMT
set-cookie	Domain=proton.me; Path=/; HttpOnly; SameSite=None; Secure; Max-Age=7776000
set-cookie	Tag=default; Path=/; SameSite=None; Secure; Max-Age=7776000
last-modified	Thu, 19 Dec 2024 15:04:47 GMT
etag	"3ab61-629a0d9de61c0-gzip"
accept-ranges	bytes
vary	Accept-Encoding
cache-control	public, max-age=1, s-maxage=5, must-revalidate
content-type	text/html; charset=utf-8
age	1
content-security-policy-report-only	default-src 'self'; media-src https://static.zdassets.com; connect-src 'self' wss: https://protonmail.zendesk.com https://ekr.zdassets.com blob: https://account.proton.me https://reports.proton.me https://.algolia.net https://.algolianet.com https://go.getproton.me; script-src 'self' blob: 'unsafe-eval' 'unsafe-inline' https://static.zdassets.com https://pmecdn.protonweb.com; style-src 'self' 'unsafe-inline' https://pmecdn.protonweb.com; font-src 'self' https://pmecdn.protonweb.com; img-src 'self' data: blob: https:; object-src 'self' data: blob:; frame-src 'self' data: blob: https://www.youtube-nocookie.com; child-src 'self' data: blob:; report-uri https://reports.proton.me/reports/csp; frame-ancestors 'self';
strict-transport-security	max-age=31536000; includeSubDomains; preload
public-key-pins-report-only	pin-sha256="CT56BhOTmj5ZIPgb/xD5mH8rY3BLo/MlhP7oPyJUEDo="; pin-sha256="35Dx28/uzN3LeltkCBQ8RHK0tlNSa2kCpCRGNp34Gxc="; report-uri="https://reports.proton.me/reports/tls"
x-frame-options	sameorigin
x-content-type-options	nosniff
x-xss-protection	0
referrer-policy	strict-origin-when-cross-origin
x-permitted-cross-domain-policies	none
onion-location	https://protonmailrmez3lotccipshtkleegetolb73fuirgj7r4o4vfu7ozyd.onion/

WWW TLS

Transport Layer Security (TLS) is the most widely used encryption protocol on the Internet. In combination with valid certificates, servers can establish trusted communication channels even with users who have never visited them before. Network attackers can't uncover what is being communicated, even when they can see all the traffic.

Test passed

Everything seems to be well configured. Well done.

TLS Configuration: protonmail.com (185.70.42.12)

Encryption protocol version determines what features are available for negotiation between client and server.Supported protocols	TLS v1.3 TLS v1.2
Servers should always enforce their own cipher suite preference, as that is the only approach that guarantees that the best possible suite is selected.Server suite preference
Shows cipher suite configuration for this protocol version.TLS v1.3 Server preference	Suite: TLS_CHACHA20_POLY1305_SHA256 Suite ID: 0x1303 Cipher name: CHACHA20 Cipher strength: 256 bits Cipher mode: AEAD Key exchange: ecdh_x25519 Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA256 TLS_CHACHA20_POLY1305_SHA256 256 bits (ECDHE 256 bits) Suite: TLS_AES_256_GCM_SHA384 Suite ID: 0x1302 Cipher name: AES Cipher strength: 256 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: ecdh_x25519 Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA384 TLS_AES_256_GCM_SHA384 256 bits (ECDHE 256 bits) Suite: TLS_AES_128_GCM_SHA256 Suite ID: 0x1301 Cipher name: AES Cipher strength: 128 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: ecdh_x25519 Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA256 TLS_AES_128_GCM_SHA256 128 bits (ECDHE 256 bits) Suite: TLS_AES_128_CCM_SHA256 Suite ID: 0x1304 Cipher name: AES Cipher strength: 128 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: ecdh_x25519 Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA256 TLS_AES_128_CCM_SHA256 128 bits (ECDHE 256 bits)
Shows cipher suite configuration for this protocol version.TLS v1.2 Server preference	Suite: TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 Suite ID: 0xcca8 Cipher name: CHACHA20 Cipher strength: 256 bits Cipher mode: AEAD Key exchange: ECDHE_RSA Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA256 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 256 bits (ECDHE 256 bits) Suite: TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 Suite ID: 0xc02f Cipher name: AES Cipher strength: 128 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: ECDHE_RSA Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA256 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 128 bits (ECDHE 256 bits) Suite: TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 Suite ID: 0xc030 Cipher name: AES Cipher strength: 256 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: ECDHE_RSA Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA384 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 256 bits (ECDHE 256 bits) Suite: TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 Suite ID: 0x9e Cipher name: AES Cipher strength: 128 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: DHE_RSA Key exchange strength: 2048 bits Forward secrecy: Yes PRF: SHA256 TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 128 bits (DHE 2048 bits) Suite: TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 Suite ID: 0x9f Cipher name: AES Cipher strength: 256 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: DHE_RSA Key exchange strength: 2048 bits Forward secrecy: Yes PRF: SHA384 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 256 bits (DHE 2048 bits)

Analysis

TLS 1.3 supported

Excellent. This server supports TLS 1.3, which is the latest revision of the TLS protocol and a significant improvement over earlier versions. Developed over a period of several years and extensively analyzed prior to the release, TLS 1.3 removed insecure features, and improved both security and performance.

TLS 1.2 supported

Good. This server supports TLS 1.2, which can provide strong security when configured correctly. This version of the TLS protocol is necessary to provide good security with a wide range of clients that don't yet support TLS 1.3.

Deprecated protocols not supported

Excellent. This server doesn't support any of the deprecated protocol (TLS 1.1 and earlier).

Strong key exchange detected

Excellent. All cipher suites on this server rely on strong key exchange. The sweet spot is 2048 bits for DHE and 256 bits for ECDHE. Putting ECDHE suites first guarantees best security and best performance.

Only strong suites supported

Excellent. This server supports only strong cipher suites, which use strong authenticated encryption and provide forward secrecy.

All TLS connections with this server satisfy Apple's CT requirements

All TLS connections established with this server satisfy Chrome's CT requirements, using certificate, TLS extension, or OCSP response as SCT transport method.

SCT transports: CERT

All TLS connections with this server satisfy Chrome's CT requirements

All TLS connections established with this server satisfy Chrome's CT requirements, using certificate, TLS extension, or OCSP response as SCT transport method.

SCT transports: CERT

DHE server parameter not reused

This server does not reuse the private value used for the Diffie-Hellman key exchange.

TLS Configuration: www.protonmail.com (185.70.42.31)

Encryption protocol version determines what features are available for negotiation between client and server.Supported protocols	TLS v1.3 TLS v1.2
Servers should always enforce their own cipher suite preference, as that is the only approach that guarantees that the best possible suite is selected.Server suite preference
Shows cipher suite configuration for this protocol version.TLS v1.3 Server preference	Suite: TLS_CHACHA20_POLY1305_SHA256 Suite ID: 0x1303 Cipher name: CHACHA20 Cipher strength: 256 bits Cipher mode: AEAD Key exchange: ecdh_x25519 Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA256 TLS_CHACHA20_POLY1305_SHA256 256 bits (ECDHE 256 bits) Suite: TLS_AES_256_GCM_SHA384 Suite ID: 0x1302 Cipher name: AES Cipher strength: 256 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: ecdh_x25519 Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA384 TLS_AES_256_GCM_SHA384 256 bits (ECDHE 256 bits) Suite: TLS_AES_128_GCM_SHA256 Suite ID: 0x1301 Cipher name: AES Cipher strength: 128 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: ecdh_x25519 Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA256 TLS_AES_128_GCM_SHA256 128 bits (ECDHE 256 bits) Suite: TLS_AES_128_CCM_SHA256 Suite ID: 0x1304 Cipher name: AES Cipher strength: 128 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: ecdh_x25519 Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA256 TLS_AES_128_CCM_SHA256 128 bits (ECDHE 256 bits)
Shows cipher suite configuration for this protocol version.TLS v1.2 Server preference	Suite: TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 Suite ID: 0xcca8 Cipher name: CHACHA20 Cipher strength: 256 bits Cipher mode: AEAD Key exchange: ECDHE_RSA Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA256 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 256 bits (ECDHE 256 bits) Suite: TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 Suite ID: 0xc02f Cipher name: AES Cipher strength: 128 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: ECDHE_RSA Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA256 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 128 bits (ECDHE 256 bits) Suite: TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 Suite ID: 0xc030 Cipher name: AES Cipher strength: 256 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: ECDHE_RSA Key exchange strength: EC ecdh_x25519 (256 bits) Forward secrecy: Yes PRF: SHA384 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 256 bits (ECDHE 256 bits) Suite: TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 Suite ID: 0x9e Cipher name: AES Cipher strength: 128 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: DHE_RSA Key exchange strength: 2048 bits Forward secrecy: Yes PRF: SHA256 TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 128 bits (DHE 2048 bits) Suite: TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 Suite ID: 0x9f Cipher name: AES Cipher strength: 256 bits Cipher block size: 128 bits Cipher mode: AEAD Key exchange: DHE_RSA Key exchange strength: 2048 bits Forward secrecy: Yes PRF: SHA384 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 256 bits (DHE 2048 bits)

Analysis

TLS 1.3 supported

Excellent. This server supports TLS 1.3, which is the latest revision of the TLS protocol and a significant improvement over earlier versions. Developed over a period of several years and extensively analyzed prior to the release, TLS 1.3 removed insecure features, and improved both security and performance.

TLS 1.2 supported

Good. This server supports TLS 1.2, which can provide strong security when configured correctly. This version of the TLS protocol is necessary to provide good security with a wide range of clients that don't yet support TLS 1.3.

Deprecated protocols not supported

Excellent. This server doesn't support any of the deprecated protocol (TLS 1.1 and earlier).

Strong key exchange detected

Excellent. All cipher suites on this server rely on strong key exchange. The sweet spot is 2048 bits for DHE and 256 bits for ECDHE. Putting ECDHE suites first guarantees best security and best performance.

Only strong suites supported

Excellent. This server supports only strong cipher suites, which use strong authenticated encryption and provide forward secrecy.

All TLS connections with this server satisfy Apple's CT requirements

All TLS connections established with this server satisfy Chrome's CT requirements, using certificate, TLS extension, or OCSP response as SCT transport method.

SCT transports: CERT

All TLS connections with this server satisfy Chrome's CT requirements

All TLS connections established with this server satisfy Chrome's CT requirements, using certificate, TLS extension, or OCSP response as SCT transport method.

SCT transports: CERT

DHE server parameter not reused

This server does not reuse the private value used for the Diffie-Hellman key exchange.

WWW Certificates

A certificate is a digital document that contains a public key, some information about the entity associated with it, and a digital signature from the certificate issuer. It’s a mechanism that enables us to exchange, store, and use public keys. Being able to reliably verify the identity of a remote server is crucial in order to achieve secure encrypted communication.

Test passed

Everything seems to be well configured. Well done.

Certificate: protonmail.com

Leaf certificate

protonmail.com
Issuer: Let's Encrypt
Not Before: 26 Oct 2024 13:13:53 UTC
Not After: 24 Jan 2025 13:13:52 UTC (expires in 1 month 1 day)
Key: RSA 4096 bits
Signature: SHA256withRSA
View details

Names	account.protonvpn.com app.protonmail.ch beta.protonmail.com mail.protonmail.com old.protonmail.com pm.me protonmail.ch protonmail.com protonvpn.com secure.protonmail.com
Subject DN	CN=protonmail.com
Subject Key Identifier	32bbb91e63a00ace9bb13ef3fd5da7ea9bea3440
Serial	4d25cea55fe482fec0129484d099c811534
Not Before	26 Oct 2024 13:13:53 UTC
Not After	24 Jan 2025 13:13:52 UTC
Validity period	90 days
Key Usage	digitalSignature, keyEncipherment
Extended Key Usage	serverAuth, clientAuth
Must Staple	No
Issuer
Issuer DN	CN=R10, O=Let's Encrypt, C=US
Certification Authority	Let's Encrypt
Validation Type	Domain Validation (DV)
Authority Key Identifier	keyid:bbbcc347a5e4bca9c6c3a4720c108da235e1c8e8
Parent Certificate	http://r10.i.lencr.org/
OCSP	http://r10.o.lencr.org
Certificate Transparency
Signed Certificate Timestamps	26 Oct 2024 14:12:24 UTC \| Google 'Xenon2025h1' log \| Qualified 26 Oct 2024 14:12:24 UTC \| Sectigo 'Mammoth2025h1' \| Qualified
Fingerprints
SHA1	a310d263cbb919a03430516392dd30ee37ed0caf
SHA256	79fa1a20e2ffa538f9915fdc8639b6c3ef21da06aafd0ec4cae93f0b6752fcb2
SPKI SHA256	f23a2234176a698890a4ab2482d909b2a47117bccdd02d1aa9f8bc0da7249e72

Analysis

Strong private key

Good. The private key associated with this certificate is secure.

Strong signature algorithm

Good. This certificate uses a strong signature algorithm.

Certificate matches hostname

Good. The provided certificate matches the expected hostnames.

Certificate dates match

Good. The certificate is valid for use at this point of time.

Certificate has not been revoked

Good. This certificate has not been revoked.

Certificate satisfies Apple's CT compliance requirements

Good. This certificate satisfies Apple's CT requirements at present.

Certificate Trust

Determining whether a certificate is considered valid is a complicated process that depends on the exact configuration of the validating party. For trust to be established, the certificate must form a chain that ends with a trusted root. In this section we evaluate the server's certificate against major root stores.

Platform	Trusted
Apple
Google AOSP
Microsoft
Mozilla

Certificate Chain

For a server certificate to be valid, it must be presented as part of a complete and valid certificate chain. The last certificate in the chain should be the root and is usually not included in the configuration.

Leaf certificate

protonmail.com | 79fa1a2 HPKP-RO-PIN
Not After: 24 Jan 2025 13:13:52 UTC (expires in 1 month 1 day)
Authentication: RSA 4096 bits (SHA256withRSA)
View details

Names	account.protonvpn.com app.protonmail.ch beta.protonmail.com mail.protonmail.com old.protonmail.com pm.me protonmail.ch protonmail.com protonvpn.com secure.protonmail.com
Subject DN	CN=protonmail.com
Subject Key Identifier	32bbb91e63a00ace9bb13ef3fd5da7ea9bea3440
Serial	4d25cea55fe482fec0129484d099c811534
Not Before	26 Oct 2024 13:13:53 UTC
Not After	24 Jan 2025 13:13:52 UTC
Validity period	90 days
Key Usage	digitalSignature, keyEncipherment
Extended Key Usage	serverAuth, clientAuth
Must Staple	No
Issuer
Issuer DN	CN=R10, O=Let's Encrypt, C=US
Certification Authority	Let's Encrypt
Validation Type	Domain Validation (DV)
Authority Key Identifier	keyid:bbbcc347a5e4bca9c6c3a4720c108da235e1c8e8
Parent Certificate	http://r10.i.lencr.org/
OCSP	http://r10.o.lencr.org
Certificate Transparency
Signed Certificate Timestamps	26 Oct 2024 14:12:24 UTC \| Google 'Xenon2025h1' log \| Qualified 26 Oct 2024 14:12:24 UTC \| Sectigo 'Mammoth2025h1' \| Qualified
Fingerprints
SHA1	a310d263cbb919a03430516392dd30ee37ed0caf
SHA256	79fa1a20e2ffa538f9915fdc8639b6c3ef21da06aafd0ec4cae93f0b6752fcb2
SPKI SHA256	f23a2234176a698890a4ab2482d909b2a47117bccdd02d1aa9f8bc0da7249e72

Intermediate certificate

R10 | 9d7c3f1
Not After: 12 Mar 2027 23:59:59 UTC (expires in 2 years 2 months)
Authentication: RSA 2048 bits (SHA256withRSA)
View details

Subject DN	CN=R10, O=Let's Encrypt, C=US
Subject Key Identifier	bbbcc347a5e4bca9c6c3a4720c108da235e1c8e8
Serial	4ba85293f79a2fa273064ba8048d75d0
Not Before	13 Mar 2024 00:00:00 UTC
Not After	12 Mar 2027 23:59:59 UTC
Validity period	1095 days
Key Usage	digitalSignature, keyCertSign, cRLSign
Extended Key Usage	clientAuth, serverAuth
Issuer
Issuer DN	CN=ISRG Root X1, O=Internet Security Research Group, C=US
Certification Authority	Let's Encrypt
Validation Type	Not Applicable
Authority Key Identifier	keyid:79b459e67bb6e5e40173800888c81a58f6e99b6e
Parent Certificate	http://x1.i.lencr.org/
CRL	http://x1.c.lencr.org/
CA certificate	Yes (pathlen 0)
Fingerprints
SHA1	00abefd055f9a9c784ffdeabd1dcdd8fed741436
SHA256	9d7c3f1aa6ad2b2ec0d5cf1e246f8d9ae6cbc9fd0755ad37bb974b1f2fb603f3
SPKI SHA256	2bbad93ab5c79279ec121507f272cbe0c6647a3aae52e22f388afab426b4adba

Root certificate

ISRG Root X1 | 96bcec0
Not After: 04 Jun 2035 11:04:38 UTC (expires in 10 years 5 months)
Authentication: RSA 4096 bits (SHA256withRSA)
View details

Subject DN	CN=ISRG Root X1, O=Internet Security Research Group, C=US
Subject Key Identifier	79b459e67bb6e5e40173800888c81a58f6e99b6e
Serial	8210cfb0d240e3594463e0bb63828b00
Not Before	04 Jun 2015 11:04:38 UTC
Not After	04 Jun 2035 11:04:38 UTC
Key Usage	keyCertSign, cRLSign
Issuer
Issuer DN	CN=ISRG Root X1, O=Internet Security Research Group, C=US
Certification Authority	Let's Encrypt
Validation Type	Self-signed
CA certificate	Yes (pathlen unlimited)
Fingerprints
SHA1	cabd2a79a1076a31f21d253635cb039d4329a5e8
SHA256	96bcec06264976f37460779acf28c5a7cfe8a3c0aae11a8ffcee05c0bddf08c6
SPKI SHA256	0b9fa5a59eed715c26c1020c711b4f6ec42d58b0015e14337a39dad301c5afc3

Analysis

Certificate chain is correct

Good. This chain contains all the right certificates and in the right order.

Certificate: www.protonmail.com

Leaf certificate

protonmail.com
Issuer: Let's Encrypt
Not Before: 28 Oct 2024 13:13:50 UTC
Not After: 26 Jan 2025 13:13:49 UTC (expires in 1 month 3 days)
Key: RSA 4096 bits
Signature: SHA256withRSA
View details

Names	.pm.me .protonmail.ch .protonmail.com .protonvpn.ch *.protonvpn.com protonmail.com
Subject DN	CN=protonmail.com
Subject Key Identifier	f1a20aff29eff87884e8070ce0568a7664d22ba5
Serial	3a68b730d5aca1cb68732c53cd6dd48dfdc
Not Before	28 Oct 2024 13:13:50 UTC
Not After	26 Jan 2025 13:13:49 UTC
Validity period	90 days
Key Usage	digitalSignature, keyEncipherment
Extended Key Usage	serverAuth, clientAuth
Must Staple	No
Issuer
Issuer DN	CN=R10, O=Let's Encrypt, C=US
Certification Authority	Let's Encrypt
Validation Type	Domain Validation (DV)
Authority Key Identifier	keyid:bbbcc347a5e4bca9c6c3a4720c108da235e1c8e8
Parent Certificate	http://r10.i.lencr.org/
OCSP	http://r10.o.lencr.org
Certificate Transparency
Signed Certificate Timestamps	28 Oct 2024 14:12:20 UTC \| Sectigo 'Mammoth2025h1' \| Qualified 28 Oct 2024 14:12:22 UTC \| Let's Encrypt 'Oak2025h1' \| Qualified
Fingerprints
SHA1	55cbfd0de696c7aa9c1cf1e2d2d28c51c5a133b7
SHA256	36a7e845d65053b3e61b70bdcc439bef149bf05425d61ea21ac7386ced1fa23b
SPKI SHA256	76bb66711da416433ca890a5b2e5a0533c6006478f7d10a4469a947acc8399e1

Analysis

Strong private key

Good. The private key associated with this certificate is secure.

Strong signature algorithm

Good. This certificate uses a strong signature algorithm.

Certificate matches hostname

Good. The provided certificate matches the expected hostnames.

Certificate dates match

Good. The certificate is valid for use at this point of time.

Certificate has not been revoked

Good. This certificate has not been revoked.

Certificate satisfies Apple's CT compliance requirements

Good. This certificate satisfies Apple's CT requirements at present.

Certificate Trust

Determining whether a certificate is considered valid is a complicated process that depends on the exact configuration of the validating party. For trust to be established, the certificate must form a chain that ends with a trusted root. In this section we evaluate the server's certificate against major root stores.

Platform	Trusted
Apple
Google AOSP
Microsoft
Mozilla

Certificate Chain

For a server certificate to be valid, it must be presented as part of a complete and valid certificate chain. The last certificate in the chain should be the root and is usually not included in the configuration.

Leaf certificate

protonmail.com | 36a7e84 HPKP-RO-PIN
Not After: 26 Jan 2025 13:13:49 UTC (expires in 1 month 3 days)
Authentication: RSA 4096 bits (SHA256withRSA)
View details

Names	.pm.me .protonmail.ch .protonmail.com .protonvpn.ch *.protonvpn.com protonmail.com
Subject DN	CN=protonmail.com
Subject Key Identifier	f1a20aff29eff87884e8070ce0568a7664d22ba5
Serial	3a68b730d5aca1cb68732c53cd6dd48dfdc
Not Before	28 Oct 2024 13:13:50 UTC
Not After	26 Jan 2025 13:13:49 UTC
Validity period	90 days
Key Usage	digitalSignature, keyEncipherment
Extended Key Usage	serverAuth, clientAuth
Must Staple	No
Issuer
Issuer DN	CN=R10, O=Let's Encrypt, C=US
Certification Authority	Let's Encrypt
Validation Type	Domain Validation (DV)
Authority Key Identifier	keyid:bbbcc347a5e4bca9c6c3a4720c108da235e1c8e8
Parent Certificate	http://r10.i.lencr.org/
OCSP	http://r10.o.lencr.org
Certificate Transparency
Signed Certificate Timestamps	28 Oct 2024 14:12:20 UTC \| Sectigo 'Mammoth2025h1' \| Qualified 28 Oct 2024 14:12:22 UTC \| Let's Encrypt 'Oak2025h1' \| Qualified
Fingerprints
SHA1	55cbfd0de696c7aa9c1cf1e2d2d28c51c5a133b7
SHA256	36a7e845d65053b3e61b70bdcc439bef149bf05425d61ea21ac7386ced1fa23b
SPKI SHA256	76bb66711da416433ca890a5b2e5a0533c6006478f7d10a4469a947acc8399e1

Intermediate certificate

R10 | 9d7c3f1
Not After: 12 Mar 2027 23:59:59 UTC (expires in 2 years 2 months)
Authentication: RSA 2048 bits (SHA256withRSA)
View details

Subject DN	CN=R10, O=Let's Encrypt, C=US
Subject Key Identifier	bbbcc347a5e4bca9c6c3a4720c108da235e1c8e8
Serial	4ba85293f79a2fa273064ba8048d75d0
Not Before	13 Mar 2024 00:00:00 UTC
Not After	12 Mar 2027 23:59:59 UTC
Validity period	1095 days
Key Usage	digitalSignature, keyCertSign, cRLSign
Extended Key Usage	clientAuth, serverAuth
Issuer
Issuer DN	CN=ISRG Root X1, O=Internet Security Research Group, C=US
Certification Authority	Let's Encrypt
Validation Type	Not Applicable
Authority Key Identifier	keyid:79b459e67bb6e5e40173800888c81a58f6e99b6e
Parent Certificate	http://x1.i.lencr.org/
CRL	http://x1.c.lencr.org/
CA certificate	Yes (pathlen 0)
Fingerprints
SHA1	00abefd055f9a9c784ffdeabd1dcdd8fed741436
SHA256	9d7c3f1aa6ad2b2ec0d5cf1e246f8d9ae6cbc9fd0755ad37bb974b1f2fb603f3
SPKI SHA256	2bbad93ab5c79279ec121507f272cbe0c6647a3aae52e22f388afab426b4adba

Root certificate

ISRG Root X1 | 96bcec0
Not After: 04 Jun 2035 11:04:38 UTC (expires in 10 years 5 months)
Authentication: RSA 4096 bits (SHA256withRSA)
View details

Subject DN	CN=ISRG Root X1, O=Internet Security Research Group, C=US
Subject Key Identifier	79b459e67bb6e5e40173800888c81a58f6e99b6e
Serial	8210cfb0d240e3594463e0bb63828b00
Not Before	04 Jun 2015 11:04:38 UTC
Not After	04 Jun 2035 11:04:38 UTC
Key Usage	keyCertSign, cRLSign
Issuer
Issuer DN	CN=ISRG Root X1, O=Internet Security Research Group, C=US
Certification Authority	Let's Encrypt
Validation Type	Self-signed
CA certificate	Yes (pathlen unlimited)
Fingerprints
SHA1	cabd2a79a1076a31f21d253635cb039d4329a5e8
SHA256	96bcec06264976f37460779acf28c5a7cfe8a3c0aae11a8ffcee05c0bddf08c6
SPKI SHA256	0b9fa5a59eed715c26c1020c711b4f6ec42d58b0015e14337a39dad301c5afc3

Analysis

Certificate chain is correct

Good. This chain contains all the right certificates and in the right order.

DANE (443)

DNS-based Authentication of Named Entities (DANE) is a bridge between DNSSEC and TLS. In one possible scenario, DANE can be used for public key pinning, building on an existing publicly-trusted certificate. In another approach, it can be used to completely bypass the CA ecosystem and establish trust using DNSSEC alone.

Feature not applicable, not implemented, or disabled

Your server doesn't support this feature.

Cookies

Cookies are small chunks of text that are sent between your browser and a website. They are often essential to the operation of the site and sometimes contain sensitive information. Session cookies sent from secure sites must be explicitly marked as secure to prevent being obtained by active network attackers.

Test passed

Everything seems to be well configured. Well done.

HTML Content

On virtually all web sites, HTML markup, images, style sheets, JavaScript, and other page resources arrive not only over multiple connections but possibly from multiple servers and sites spread across the entire Internet. For a page to be properly encrypted, it’s necessary that all the content is retrieved over HTTPS. In practice, that’s very often not the case, leading to mixed content security problems.

Test passed

Everything seems to be well configured. Well done.

Encryption of Embedded Resources

In this section we look at the transport security of all embedded resources. Mixed active content occurs when there are unprotected scripts or styles embedded in a page. This is typically not allowed by modern browsers. Mixed passive content (images, videos and such) are typically allowed, but shouldn't be present.

0 script(s)
0 out of 0 are secure

0 CSS file(s)
0 out of 0 are secure

0 media file(s)
0 out of 0 are secure

Encryption of Outbound Links

Ideally, an encrypted page should only have links that lead to other encrypted pages. If plaintext links are used, passive network attackers can see where people go after they visit your web site. It's also possible that some sensitive information is leaked in the Referer header.

0 link(s)
0 out of 0 are encrypted

HTTP Strict Transport Security

HTTP Strict Transport Security (HSTS) vastly improves security of the network encryption layer. With HSTS enabled, browsers no longer allow clicking through certificate warnings errors, which are typically trivial to exploit. Additionally, they will no longer submit insecure (plaintext) requests to the site in question, even if asked.

Test passed

Everything seems to be well configured. Well done.

HSTS Policy Main host

URL from which this policy was obtained.Location	https://www.protonmail.com/
Specifies policy duration. Once activated, HSTS stays in force until this time lapses. Browsers update policy cache duration every time they receive a new HSTS header from a site.max‑age	31,536,000 seconds (about 1 year)
When present, this directive forces HSTS activation on allsubdomains. For best security, HSTS should be deployed on the bare domain name (e.g., example.com) and all its subdomains.includeSubDomains
Presence of this directive indicates that a web site wishes to permanently use HSTS and that its policy information should be preloaded (embedded in browsers).preload

Analysis

Policy is valid

OK. Your HSTS policy uses correct syntax.

Long policy age

Your HSTS policy has a long max-age value, which offers better protection.

Policy covers subdomains

When subdomains are included, network attackers are unable to manufacture arbitrary subdomains to manipulate cookies and trick users.

Redirection from HTTP to HTTPS is to a parent host that activates HSTS

For simplicity, it's best when there is a redirection on port 80 that sends clients to the same host on port 443. In that case, you know that HSTS will always be activated on the host. There isn't a same-host redirection in this instance, but the redirection is to a parent that activates HSTS via the includeSubDomains directive. That's all right.

Starting point: http://www.protonmail.com

Current redirection: https://protonmail.com

Policy preloaded

Excellent. This host is covered by a preloaded HSTS policy.

Preloaded host: protonmail.com; includeSubDomains=true

HSTS Policy Apex host

URL from which this policy was obtained.Location	https://protonmail.com/
Specifies policy duration. Once activated, HSTS stays in force until this time lapses. Browsers update policy cache duration every time they receive a new HSTS header from a site.max‑age	31,536,000 seconds (about 1 year)
When present, this directive forces HSTS activation on allsubdomains. For best security, HSTS should be deployed on the bare domain name (e.g., example.com) and all its subdomains.includeSubDomains
Presence of this directive indicates that a web site wishes to permanently use HSTS and that its policy information should be preloaded (embedded in browsers).preload

Analysis

Policy is valid

OK. Your HSTS policy uses correct syntax.

Long policy age

Your HSTS policy has a long max-age value, which offers better protection.

Policy covers subdomains

When subdomains are included, network attackers are unable to manufacture arbitrary subdomains to manipulate cookies and trick users.

Preload intent declared

Good. With the preload directive set, browsers have a green light to embed the HSTS policy.

Redirection from HTTP to HTTPS to the same host

Good. The redirection from HTTP to HTTPS is to the same host. This approach ensures that HSTS is activated on the hostname when it's accessed via plaintext.

Policy preloaded

Excellent. This host is covered by a preloaded HSTS policy.

Preloaded host: protonmail.com; includeSubDomains=true

HTTP Public Key Pinning

HTTP Public Key Pinning (HPKP) enables site operators to restrict which certificates are considered valid for their domain names. With a valid HPKP configuration, sites can defeat man in the middle (MITM) attacks using fraudulent or misissued certificates. HPKP is an advanced feature, suitable for use by only high-profile web sites.

Feature not applicable, not implemented, or disabled

Your server doesn't support this feature.

HPKP Policy (Reporting Only)

This directive signals to the user agent that the pinning policy applies to the current host as well as all its subdomains.includeSubDomains
Contains the URI to which user agents should report pinning policy violations.report-uri	https://reports.proton.me/reports/tls
Specifies a cryptographic identity that should be bound to the given web host. The binding is done via the hash of the desired public key. pin-sha256	8joiNBdqaYiQpKskgtkJsqRxF7zN0C0aqfi8DacknnI=
Specifies a cryptographic identity that should be bound to the given web host. The binding is done via the hash of the desired public key. pin-sha256	drtmcR2kFkM8qJClsuWgUzxgBkePfRCkRpqUesyDmeE= Leaf certificate: RSA 4096 bits Subject: CN=protonmail.com Issuer: CN=R10, O=Let's Encrypt, C=US protonmail.com (RSA 4096 bits)

Analysis

Subdomains not covered by policy

Pinning policies that don't cover subdomains are potentially vulnerable to active network attacks involving cookies. Because the cookie specification is lax, it's possible that active network attackers abuse and even "create" subdomains to use for attack.

Analysis

Report-only policy discovered

Header: public-key-pins-report-only

Value: pin-sha256="8joiNBdqaYiQpKskgtkJsqRxF7zN0C0aqfi8DacknnI="; pin-sha256="drtmcR2kFkM8qJClsuWgUzxgBkePfRCkRpqUesyDmeE="; report-uri="https://reports.proton.me/reports/tls"

Report-only policy is valid

Good. Your policy uses the correct syntax.

Content Security Policy

Content Security Policy (CSP) is a security mechanism that allows web sites control how browsers process their pages. In essence, sites can restrict what types of resources are loaded and from where. CSP policies can be used to defend against cross-site scripting, prevent mixed content issues, as well as report violations for investigation.

Feature not applicable, not implemented, or disabled

Your server doesn't support this feature.

Subresource Integrity

Subresource Integrity (SRI) is a new standard that enables browsers to verify the integrity of embedded page resources (e.g., scripts and stylesheets) when they are loaded from third-party web sites. With SRI deployed, remote resources can be used safely, without fear of them being modified by malicious parties.

Test passed

Everything seems to be well configured. Well done.

No external scripts
SRI not needed

No external stylesheets
SRI not needed

Analysis

No remote resources

The homepage of this site doesn't contain any remote resources so SRI is not needed.

Expect CT

Expect-CT is a deprecated response HTTP header designed to enable web sites to monitor problems related to their Certificate Transparency (CT) compliance. Should any CT issues arise, browsers that supported this header will submit reports to the specified reporting endpoint. Chrome was the browser that introduced support for this response header, but later deprecated it and removed it in version 107.

Feature not applicable, not implemented, or disabled

Your server doesn't support this feature.

Analysis

Deploy Expect-CT to enable reporting

An Expect-CT policy enables web sites to monitor for any problems related to their Expect-CT compliance, detecting potentially serious issues quickly. When issues arise, compliant browsers will submit reports to the specified reporting endpoints. Before CT became required for all public certificates the Expect-CT was also used to require CT, but that use case no longer applies.

Frame Options

The X-Frame-Options header controls page framing, which occurs when a page is incorporated into some other page, possibly on a different site. If framing is allowed, attackers can employ clever tricks to make victims perform arbitrary actions on your site; they do this by showing their web site while forwarding the victim's clicks to yours.

Test passed

Everything seems to be well configured. Well done.

Analysis

Header information

Name: x-frame-options

Value: deny

Framing blocked

Good. Your site doesn't allow page framing from any other page.

XSS Protection

Some browsers ship with so-called XSS Auditors, built-in defenses against XSS. Although these defenses work against simple reflective XSS attacks, they can be abused by skillful attackers to add weaknesses to otherwise secure web sites. These dangers are present in both filtering and blocking modes. At this time, the Safari browser ships with its XSS defenses enabled by default. For this reason, the best approach is to explicitly disable this functionality.

Test passed

Everything seems to be well configured. Well done.

Analysis

Header information

Name: x-xss-protection

Value: 0

Browser XSS protection disabled

Great. XSS protection is explicitly disabled, making this web site safe even with browsers that have this functionality enabled by default.

Content Type Options

Some browsers use a technique called content sniffing to override response MIME types provided by HTTP servers and interpret responses as something else (usually HTML). This behavior, which could potentially lead to security issues, should be disabled by attaching an X-Content-Type-Options header to all responses.

Test passed

Everything seems to be well configured. Well done.

Analysis

Header information

Name: x-content-type-options

Value: nosniff

Valid configuration

Good. Your configuration is valid. This means that browsers won't try to guess file MIME type on this web site.

Public Report | protonmail.com

protonmail.com

Domain Name System

Email

WWW

DNS Zone

Nameserver Names

Nameserver Addresses

Start of Authority (SOA) Record

Analysis

Backing DNS Queries

DNS Records

DNS Records

Backing DNS Queries

DNSSEC

Analysis

Useful DNSSEC Tools

Certification Authority Authorization

CAA Policy Information

Analysis

Email (SMTP)

Analysis

Email TLS (SMTP)

TLS Configuration: mail.protonmail.ch (185.70.42.128) Cached

Analysis

TLS Configuration: mail.protonmail.ch (176.119.200.128) Cached

Analysis

TLS Configuration: mail.protonmail.ch (185.205.70.128) Cached

Analysis

TLS Configuration: mailsec.protonmail.ch (185.205.70.129) Cached

Analysis

TLS Configuration: mailsec.protonmail.ch (185.70.42.129) Cached

Analysis

TLS Configuration: mailsec.protonmail.ch (176.119.200.129) Cached

Analysis

Email Certificates (SMTP)

Certificate #1 Cached

Analysis

Certificate Chain

Analysis

Email DANE (SMTP)

DANE: mail.protonmail.ch (185.70.42.128)

Analysis

DANE: mail.protonmail.ch (176.119.200.128)

Analysis

DANE: mail.protonmail.ch (185.205.70.128)

Analysis

DANE: mailsec.protonmail.ch (185.205.70.129)

Analysis

DANE: mailsec.protonmail.ch (185.70.42.129)

Analysis

DANE: mailsec.protonmail.ch (176.119.200.129)

Analysis

SPF

SPF Policy Information Main policy

Analysis

SPF Policy Information Included policy

SPF Policy Information Included policy

DMARC

DMARC Policy Information

Analysis

MTA Strict Transport Security

MTA-STS Policy Indicator

Analysis

MTA-STS Policy

Analysis

Certificate: mta-sts.protonmail.com

Analysis

Certificate Chain

Analysis

SMTP TLS Reporting

TLS-RPT Policy

Analysis

HTTP (80)

URL: http://protonmail.com/

Analysis

URL: http://www.protonmail.com/

Analysis

HTTP (443)

URL: https://protonmail.com/