ProtonBlog

Proton Mail’s SSL Certificate

Share this page

UPDATE 11 October 2021: We are now using Let’s Encrypt(new window) as the Certificate Authority that verifies the SSL certificates used to secure the Proton Mail and Proton VPN web sites. For more information on this, and for instructions on how to check the validity of our certificate, please see Proton Mail’s TLS/SSL Certificate(new window).

Proton Mail is all about privacy and we want to do our best to protect everyone’s data and communication. When accessing proton.me, the transmission of information between your browsers and our servers in Switzerland is always encrypted and protected by HTTPS(new window). While this is not the same as the end-to-end encryption concept of PGP, it is nevertheless important for protecting you from man-in-the-middle attacks and other forms of communication eavesdropping.

For HTTPS, each website has a SSL certificate that is verified by a trusted certificate authority. The certificate authority that vouches for Proton Mail is QuoVadis Trustlink Schweiz AG(new window), which is a subsidiary of the Swiss postal service. A modern browser should automatically check the validity of the certificate of a HTTPS protected website and alert you if it detects something untrustworthy. For the uber security conscious users who want to manually check, the SHA1 hash/fingerprint/thumbprint of our certificate is:

0C 13 D9 0D 85 8A B7 8D 14 5E 9C 59 5B FE 2D 2E 3D 67 86 51

The fingerprint for app.proton.me is:

95 20 1C 7D 7D 3D BE E4 4E EF AB 93 00 A1 E3 45 F5 AB A8 59

If this matches what you see in your browser, then you know you are communicating with the real Proton Mail website and using the correct public key to encrypt your sensitive information and only Proton Mail can decrypt it.

You can check it in Chrome as follows:

Click on the lock button in front of the URL.

Go to Connection and click on Certificate Information.

In Details, show All and verify the Thumbprint matches the one above (make sure you are looking at the certificate for proton.me, not QuoVadis Trustlink Schweiz AG(new window) ).

You can check it in Firefox as follows:

Click on the lock button in front of the URL and click on More Information.

Go to Security and click on View Certificate.

In General, verify the SHA1 Fingerprint matches the one above (make sure you are looking at the certificate for proton.me, not QuoVadis Trustlink Schweiz AG(new window)).

We will continue to improve our security protocols and roll out more security features as we scale up. Thanks for all the interest and help from the community!

Sign up and get a free encrypted email account from Proton Mail.

Protect your privacy with Proton
Create a free account

Share this page

Proton Team

We are scientists, engineers, and specialists from around the world drawn together by a shared vision of protecting freedom and privacy online. Proton was born out of a desire to build an internet that puts people before profits, and we're working to create a world where everyone is in control of their digital lives.

Related articles

Last week, the Spanish Presidency of the European Council delayed a vote regarding the Council’s position on the controversial Child Sexual Abuse Regulation (CSAR) due to a lack of consensus over the issue of encryption, among others. This proposed r
At Proton, we’re always working on new and innovative ways to protect the privacy and data of the Proton community. Sometimes that means developing entirely new services, like our Proton Sentinel program, which combines AI and human security analysts
How to unsend an email in Gmail, Outlook, Proton Mail, and Apple Mail
“Undo Send” gives you a chance to stop an erroneous message you’ve just sent. We’ve all done it. You hit Send on an email only to spot you’ve misspelled someone’s name, forgotten an attachment, or accidentally sent a cringing joke to half your conta
Google has already taken privacy washing to the extreme by trying to brand itself as “privacy focused”, even though its business model is based on surveillance.  Lately, the company’s marketing strategy has turned toward outright Orwellian doublespe
Last week, the UK government made a statement in the House of Lords acknowledging that portions of the controversial Online Safety Bill might not even be technically enforceable without breaking end-to-end encryption. This rightly received a lot of a
What is email spoofing?
Email spoofing is a technique attackers use to make a message appear to be from a legitimate sender — a common trick in phishing and spam emails. Learn how spoofing works, how to identify spoofed messages, and how to protect yourself from spoofing a