Messages are stored on ProtonMail servers in encrypted format. They are also transmitted in encrypted format between our servers and user devices. Messages between ProtonMail users are also transmitted in encrypted form within our secure server network. Because data is encrypted at all steps, the risk of message interception is largely eliminated.
ProtonMail's zero access architecture means that your data is encrypted in a way that makes it inaccessible to us. Data is encrypted on the client side using an encryption key that we do not have access to. This means we don't have the technical ability to decrypt your messages, and as a result, we are unable to hand your data over to third parties. With ProtonMail, privacy isn't just a promise, it is mathematically ensured. For this reason, we are also unable to do data recovery. If you forget your password, we cannot recover your data.
We use only secure implementations of AES, RSA, along with OpenPGP. Furthermore, all of the cryptographic libraries we use are open source. By using open source libraries, we can guarantee that the encryption algorithms we are using do not have clandestinely built in back doors. ProtonMail's open source software has been thoroughly vetted by security experts from around the world to ensure the highest levels of protection.
All user data is protected by the Swiss Federal Data Protection Act (DPA) and the Swiss Federal Data Protection Ordinance (DPO) which offers some of the strongest privacy protection in the world for both individuals and corporations. As ProtonMail is outside of US and EU jurisdiction, only a court order from the Cantonal Court of Geneva or the Swiss Federal Supreme Court can compel us to release the extremely limited user information we have.
We have invested heavily in owning and controlling our own server hardware so your data never goes to the cloud. Our data centers are located at highly secure sites that require biometric access. This provides an extra layer of protection by ensuring your encrypted emails are not easily accessible to any third parties. On a system level, our servers utilize fully encrypted hard disks with multiple password layers so data security is preserved even if our hardware is seized.
Unlike competing email services, we do not track you. As we have no way to read encrypted emails, we also do not serve targeted advertisements or build profiles with your personal data. For extra privacy for users in sensitive professions (journalists or activists), we also provide an anonymous email gateway.
You can set an optional expiration time on ProtonMail’s encrypted emails, so they will be automatically deleted from the recipient’s inbox once they have expired. This technology works for both emails sent to other ProtonMail users, and encrypted emails sent to non-ProtonMail email addresses. Similar to SnapChat, we’ve added a way for you to have ephemeral communication.
We use SSL to secure communication between our server and your computer. Message data between our server and your computer is already sent encrypted, but we use SSL to add another layer of protection and to ensure that the web page your browser loads is not tampered with by a third party intercepting your traffic in a MITM (Man in the Middle) attack.
Our TLS certificate authority (CA) is Let's Encrypt, the world's largest TLS certificate issuer. Let's Encrypt's goal of encrypting every connection on the web and its use of open standards wherever possible align with our vision of creating an internet where privacy is the default. To allow extremely security conscious users to further verify that they are in fact connecting to our server, we have also released SHA1 and SHA-256 hash for our TLS public key.
We support sending encrypted communication to non-ProtonMail users via symmetric encryption. When you send an encrypted message to a non-ProtonMail user, they receive a link which loads the encrypted message onto their browser, which they can decrypt using a passphrase that you have shared with them. You can also send unencrypted messages to Gmail, Yahoo, Outlook and others, just like regular email.
We created ProtonMail because we found that none of the existing secure email services available today are sufficiently secure. However, a secure service like ProtonMail cannot improve the security landscape if it is so difficult to use, nobody can use it. From the start, we designed ProtonMail with a strong emphasis on usability. As a result, ProtonMail is very easy to use. There is nothing to install, and no encryption keys to manage, if you can use Gmail, Thunderbird, or Outlook, you can use ProtonMail.