On Thursday 17 March 2005 05:42 am, Ben Laurie wrote:
Jon Callas wrote:
It's a small thing, but if message A has one attachment,
"Attachment.pgp", and message B has two attachments, "Text.pgp" and
"ZeSecretPlans.doc.pgp" -- which each decompose to the same mail message
-- one could argue that message A is more secure than message B because
it leaks less information about its internal structure.
Are attachment names really not encrypted? If they are (as they should
be) then the only threat is that an attacker knows the number and
(compressed) size of the attachments. I find it hard to get excited
about that.
Implementations differ. I've seen some implementations that split out the
mime parts that obfuscate the attachment names and others that just add .pgp
or .asc to the attachment names.
I think that one of the larger issues is that if the mime parts are separate,
an attacker could remove a single attachment, effectively changing part of
the meaning of what the original sender wanted to say by removing part of the
message.
Regards,
- Brian