ProtonBlog(new window)

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(new window)

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

Can you password-protect a folder in Google Drive?
Protecting a folder with a password is a simple yet effective way of securing files. You may wonder whether you can password-protect a folder in Google Drive. We explain what access controls Google Drive offers and what you can do to improve your sec
Proton Pass now supports passkeys on all devices and plans
We’re excited to announce that Proton Pass supports passkeys for everyone, allowing you to manage and use passkeys across all devices seamlessly. Passkeys are an easy and secure alternative to traditional passwords that can help prevent phishing atta
what is a passkey?
Passkeys are a new way to secure your online accounts using cryptographic keys instead of passwords. They offer a high level of convenience and security, and are a real game-changer in the way we access and secure sites. What is a passkey, though, an
Apple’s marketing team has built a powerful association between the iPhone and privacy. The company’s ad campaigns claim that “what happens on your iPhone, stays on your iPhone.” And, “Privacy. That’s iPhone.” But Apple’s lawyers are telling a diffe
A cyberattack on national public employment service France Travail has exposed the personal data of as many as 43 million people.  The latest breach is the second major cybersecurity attack to happen in France in the past month, raising concerns abo
If I share a folder in Google Drive, can anybody see my other folders
Google Drive makes it easy to share files and folders, but you may have wondered at some point whether the people you’ve shared a folder with can see your other folders. We answer this question below and also share some tips for truly secure link sha
In 2014, Proton Mail was introduced as a web app, revolutionizing how we think about email privacy. Today, we’re excited to broaden the horizons of secure communication by launching the Proton Mail desktop app. Anyone can now use the new Proton Mail