6.5 Signed and Encrypted Messages

You can read encrypted or signed PGP or GPG messages with MH-E²¹. This section assumes that you already have a good understanding of GPG and have set up your keys appropriately.

If someone sends you a signed message, here is what you’ll see:

[[PGP Signed Part:Bill Wohler <wohler@stop.mail-abuse.org>]]
This is a signed message.

[[End of PGP Signed Part]]

If the key for the given signature is not in your keychain, you’ll be given the opportunity to fetch the key from a key server and verify the key. If the message is really large, the verification process can take a long time. You can press C-g at any time to cancel²².

If the signature doesn’t check out, you might see something like this:

[[PGP Signed Part:Failed]]
This is a signed message.
This is garbage added after the signature was made.

[[End of PGP Signed Part]]

If someone sends you an encrypted message, MH-E will ask for your passphrase to decrypt the message. You should see something like this:

[[PGP Encrypted Part:OK]]

[[PGP Signed Part:Bill Wohler <wohler@stop.mail-abuse.org>]]
This is the secret message.

[[End of PGP Signed Part]]

[[End of PGP Encrypted Part]]

If there is a problem decrypting the message, the button will say:

[[PGP Encrypted Part:Failed]]

You can read the contents of this button using the methods described in Viewing Attachments. If the message were corrupted, you’d see this:

[[PGP Encrypted Part:Failed]
Invalid base64 data]

If your passphrase were incorrect, you’d see something like this:

[GNUPG:] ENC_TO CD9C88BB610BD9AD 1 0
[GNUPG:] USERID_HINT CD9C88BB610BD9AD Bill Wohler <wohler@stop.mail-abuse.org>
[GNUPG:] NEED_PASSPHRASE CD9C88BB610BD9AD CD9C88BB610BD9AD 1 0
[GNUPG:] BAD_PASSPHRASE CD9C88BB610BD9AD
gpg: encrypted with 1024-bit RSA key, ID 610BD9AD, created 1997-09-09
      "Bill Wohler <wohler@stop.mail-abuse.org>"
gpg: public key decryption failed: bad passphrase
[GNUPG:] BEGIN_DECRYPTION
[GNUPG:] DECRYPTION_FAILED
gpg: decryption failed: secret key not available
[GNUPG:] END_DECRYPTION

gpg exited abnormally: '2'

The appearance of the buttons is controlled by the faces mh-show-pgg-good, mh-show-pgg-bad, and mh-show-pgg-unknown depending on the validity of the signature. The latter is used whether the signature is unknown or untrusted.