ProtonMail announced two new security related features and improvements yesterday available to all users of the secure email provider.

Address Verification is a new security feature that leverages ProtonMail's Encrypted Contacts feature. Encrypted Contacts allows you to trust public keys of contacts so that the contacts data is encrypted and digitally signed.

ProtonMail states that no one can tamper with the data once it has been trusted; this eliminates the risk associated with a compromise of the ProtonMail service and the sending of fake public encryption keys to read confidential messages.

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The default state on ProtonMail is that the service distributes cryptographic keys needed for communication; this was done to make the process as straightforward as possible.

When ProtonMail users use the new security feature, use of specific keys can be enforced which the ProtonMail server or anyone else cannot change or tamper with.

To configure trusted keys for a particular user on ProtonMail do the following:

  1. Go to Contacts.
  2. Select the contact from the list that you want to configure trusted keys for.
  3. Click on the advanced settings gear icon next to the email address.
  4. Toggle Trusted Keys to on, and select the key from the list of available public keys, that you want to trust.

Trusted senders have a special icon attached to their email address to indicate the enhanced security status.

ProtonMail users can check out this help article on the ProtonMail website for additional information.

Full PGP Support

The second new feature that ProtonMail launched improves PGP Support. The cryptography that ProtonMail uses is based on PGP.

The two new additions to PGP support are:

Option to import public keys from contacts to send PGP encrypted emails to non-ProtonMail contacts.
Export your public ProtonMail PGP key and share it with non-ProtonMail contacts so that they can send you PGP email to your account.
ProtonMail launched a new public key server that should make key discovery even easier. For ProtonMail customers, the process is automatic and Address Verification can be used to make it more secure. For non-ProtonMail users, it is now possible to grab the public key of ProtonMail users if they could not retrieve it through other means.

The address of the public key server is hkps://api.protonmail.ch. Note that it cannot be accessed through the browser. Public keys can be downloaded directly by using https://api.protonmail.ch/pks/lookup...protonmail.com