The first* is used to authenticate the user and to retrieve the correct account, and the second is kept only by the user, and is used to decrypt their mailbox. ProtonMail accounts are protected by two passwords. The SSL certificates are signed by SwissSign. Next, ProtonMail uses end-to-end encryption for encrypted messages, using secure implementations of the open source AES, RSA, and OpenPGP libraries including, TLS 1.0, AES-128 CBC, DHE RSA handshake, and SHA3 hash authentication. The servers themselves make use of fully encrypted hard disks with multiple password layers, so data security is preserved even if the hardware is seized or compromised. This means that ProtonMail staff have no access to the data. First of all email is stored encrypted on servers.

Secure servicesWhen you use ProtonMail, there are many layers of protection securing your data. ProtonMail is high up the list for secure email services, and for good reason. With everyday threats to data, more and more people are opting for encrypted services. ProtonMail has been created to bring encrypted email to everyone across the globe.

Proton email storage limit