#338 Signing and PGP/MIME both fail with "Bcc:" recipients

[Andreas Renberg (IQAndreas)]

Signing messages and using the PGP/MIME feature works great when sending only to To: recipients. However, if there is a single Bcc: recipient, (1) the message fails signing, (2) even though Force PGP/MIME is set, the message will always be sent and delivered as inline PGP.

I have attached one of the emails I sent with one "Bcc:" recipient. In addition, I started off by creating this thread which contains more details:

• Unable to use PGP/MIME on messages with only Bcc recipients

[Andreas Renberg (IQAndreas)]

Problem (2) may or may not be related, and I'm afraid I'm not sure how to debug or dig deeper into that problem.

I can, however, give more details regarding problem (1). This is my master key and subkeys (I added the # to show that the secret key for the master signing key is stored offsite):

pub#  4096R/0x8BBB5F64  created: 2014-09-23  expires: 2015-05-01  usage: SC  
                               trust: ultimate      validity: ultimate
sub   4096R/0x3C60C17E  created: 2014-09-23  expires: 2015-05-01  usage: E   
sub   4096R/0xA4E7D55C  created: 2014-09-23  expires: 2015-05-01  usage: S

Messages sent with only To: recipients in Thunderbird and Enigmail show up as good signatures (notice the master signing key, 0x8BBB5F64 is being mentioned):

Enigmail Security Info

Good signature from Andreas Renberg (IQAndreas) <withdrawn>
Key ID: 0x8BBB5F64 / Signed on: 09/24/2014 04:00 AM
Key fingerprint: E82F 46DD 8613 3D80 FDB8 A797 0E20 7194 8BBB 5F64</withdrawn>

Whereas, if the message has a single Bcc: recipient, the message checking fails with this message (notice the signing subkey, 0xA4E7D55C being mentioned):

Enigmail Security Info

Error - signature verification failed
Public key 54A94635A4E7D55C needed to verify signature

BAD signature from Andreas Renberg (IQAndreas) <withdrawn></withdrawn>

[Patrick Brunschwig]

fixed on master