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OpenPGP

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the-djmaze edited this page Nov 2, 2022 · 7 revisions

When OpenPGP is enabled by admin, you will have options to encrypt, decrypt, sign and verify messages.

These can be achieved with: Mailvelope, OpenPGP.js and GnuPG. Difference is that GnuPG runs on the server and the others in your browser.

Sign

Signing a message requires the passphrase of your private key. For safety the system will first check if it is possible with OpenPGP.js else GnuPG.

OpenPGP.js

  • Sign only text/html
  • Not the attachments
  • Done in browser so that server doesn't need your passphrase
  • This is the primary choice

GnuPG

  • Sign everything
  • Done on server, passphrase less secure as it is transmitted (https recommended)
  • This is the secondary choice

Mailvelope

Not possible

Encrypt

Encrypting a message doesn't need a passphrase, because that is done with public keys. The system will first try GnuPG else OpenPGP.js.

GnuPG

  • Encrypt everything
  • Done on server, send to server unencrypted (https recommended)
  • This is the primary choice

OpenPGP.js

  • Encrypt only text/html
  • Not the attachments
  • Done in browser, so send to server encrypted
  • This is the secondary choice

Mailvelope

Use the special button in compose window to activate.

  • Encrypt only text & attachments
  • HTML not possible
  • Done in browser, so send to server encrypted

Sign and Encrypt

This combination is also possible and follows the above rules. For a good understanding we explain each possible method.

OpenPGP.js sign + GnuPG encrypt

This is the primary choice used as it follows all above mentioned rules.

OpenPGP.js

Happens when GnuPG is not installed on the server or doesn't have all required public keys.

GnuPG

Happens when OpenPGP.js doesn't have the private key to sign messages.

Mailvelope

Not possible, because you can't select the private key to sign with. Only the default key is used and that is an issue when sending from different e-mail addresses then the Mailvelope default on and we can't see which is the default.

GnuPG notes

On the server GnuPG is used in one of two ways:

  • As PHP extension https://php.net/gnupg and must be version 1.5+
  • Else using the system command gpg when it is found using which gpg or in some bin directories

To know which your server is using, go to SnappyMail Admin -> About. There it will show a cross or check for GnuPG.

  • ✔ = PHP GnuPG extension is used
  • ❌ = gpg command line is used
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