When using (Thunderbird and) GnuPG to send a PGP/MIME message to two separate recipients, with the text body different in both messages, but the same file attached to both of them, does this give an outside attacker that observes the traffic any additional advantage without knowledge of the plain text?
I realize that this allows attacker to guess I sent the same file (emails beyond a certain size can be guessed to contain attached files anyway). But what I am interested in is whether this gives an attacker a tangible advantage of any kind that could allow to retrieve the plain text?
Keys used are RSA, recipient key is 2k, mine is 4k.