[MlMt] retry decrypt

[Randy Bush]

>> a gpg encrypted message arrives.  i try my default key and fail.  i
>> realize the sender has encrypted to a different key.  i can not figure
>> out how to get mm to let be retry the decryption.
>> 
>> clue?
> 
> Can this even be a thing???
> 
> It seems (based on what I see in the "Show Details" display of MM for
> encrypted messages) that an encrypted message carries metadata about
> which keys it is encrypted to, so GPG (called by MM ) is not going to
> try the wrong key. For example, here's what a recent message's
> "details" were:
> 
> ENC_TO D62C868FA61CAFA9 1 0
> ENC_TO FD844AB0476CD12E 16 0
> KEY_CONSIDERED 83EB18298975A0BBD8578A52DACD422676ABC38C 0
> PINENTRY_LAUNCHED 38376 mac 1.1.0 - - -
> KEY_CONSIDERED 83EB18298975A0BBD8578A52DACD422676ABC38C 0
> DECRYPTION_KEY BC83DEE8C839B9F55D6EE253FD844AB0476CD12E
> 83EB18298975A0BBD8578A52DACD422676ABC38C u
> KEY_CONSIDERED 1D77E507FB3967DFF4AFCA79AC49A3964DD8597D 0
> NO_SECKEY D62C868FA61CAFA9
> KEY_CONSIDERED 83EB18298975A0BBD8578A52DACD422676ABC38C 0
> BEGIN_DECRYPTION
> DECRYPTION_INFO 2 9
> PLAINTEXT 74 1557324053
> DECRYPTION_OKAY
> GOODMDC
> END_DECRYPTION
> 
> The "ENC_TO" lines are the key IDs of sub-keys for the one o0f
> sender's keys and one of mine. GPG finds both key IDs in my keychain,
> but only has a secret key for mine, which it uses for decryption.

one only looks at the details *after* the decrypt fails.

idiots such as i do not read the key name in the pop-up before entering
the 'normal' (whatever that is) passphrase.  then it fails.  then i can
not go back and pay attention and do it properly.

randy