Nikos Mavrogiannopoulos <[email protected]> writes: > btw. It would be nice if the list would notify the poster when > messages are being held.
It's intended to do that, but I'm not very good at mailman configuration, so I guess I have messed that up somehow. > Also please use Nikos for my name. Noted, sorry about that. > Do you think the current function could provide information on the > plaintext? From a quick look it is not obvious to me, but I haven't > checked thoroughly. The poly_hash function clearly has data-dependent timing. If it is useful for the attacker, I don't know. > Note that the current limit on the code is 16MB messages per tag, not > per key, so it is oversufficient for all practical uses of a MAC > (which is not the same as a hash). I consider handling of large files to be an important application of any MAC. When encrypting a large file (typical cases: session key derived from a passphrase, or random session key encrypted with RSA), the session key should always include a MAC key for authenticating the data. And streaming operation is important, and then you don't even know in advance if the file is going to be small or large. > I haven't checked but if adding support for larger messages per tag > would reduce performance, but if this is the case I think it would be > pretty counter-productive. It should make no difference for short messages. The "layer-2" hashing for large messages will be some four times slower than for short messages. Not sure what the overall slowdown would be; the layer-2 work may still be a small fraction of the time spent in the layer-1 hashing. Regards, /Niels -- Niels Möller. PGP-encrypted email is preferred. Keyid C0B98E26. Internet email is subject to wholesale government surveillance. _______________________________________________ nettle-bugs mailing list [email protected] http://lists.lysator.liu.se/mailman/listinfo/nettle-bugs
