ProtonMail is the world’s largest encrypted email provider with over 2 million users worldwide. Its popularity exploded just after the US presidential election, its users include journalists, activists, businesses, and normal people that want to protect their security and privacy. The service is a free and open source, featuring strong end-to-end encryption and protected by Swiss privacy laws.
Implementing a Tor hidden service for ProtonMail Tor has numerous advantages for end-users, communications are protected by supplementary layers of encryption, user’ IP address is masqueraded by the anonymizing network, and such kind of service is able to bypass government censorship.
“There are several reasons why you might want to use ProtonMail over Tor. First, routing your traffic to ProtonMail through the Tor network makes it difficult for an adversary wiretapping your internet connection to know that you are using ProtonMail. Tor applies extra encryption layers on top of your connection, making it more difficult for an advanced attacker to perform a man-in-the-middle attack on your connection to us. Tor also makes your connections to ProtonMail anonymous as we will not be able to see the true IP address of your connection to ProtonMail.” a onion site,” ProtonMail explained in a blog post.
“Tor can also help with ProtonMail accessibility. If ProtonMail becomes blocked in your country, it may be possible to reach ProtonMail by going to our onion site. Furthermore, onion sites are “hidden” services in the sense that an adversary cannot easily determine their physical location. Thus, while protonmail.com could be attacked by DDoS attacks, protonirockerxow.onion cannot be attacked in the same way because an attacker will not be able to find a public IP address.”
The onion address for the ProtonMail Tor service:
Just for curiosity, the above address was generated by the company used spare CPU capacity to generate millions of encryption keys and then hashed them aiming to generate a more human readable hash. The address it can be easily remembered as:
proton i rocker xow
The ProtonMail hidden service only accepts HTTPS connections, it uses a digital certificate issued by Digicert, the same CA used by Facebook for its Tor hidden service.
The ProtonMail hidden service could be reached via a desktop web browser and both iOS and Android apps.
(Security Affairs – ProtonMail, Tor)