Field slide attacks and how to avoid them.
Amir Herzberg
AMIR at newgenpay.com
Sun Sep 9 02:49:02 EDT 2001
John says,
> I've been noticing a lot of ways you can mess up a cryptographic
> protocol due to the "sliding around" of fields within a
> signed or MACed
> message. The classic example of this is the old attack on PGP
> fingerprints, which let you use some odd keysize, and thus get two
> different keys (with different keysizes) with the same hash, without
> breaking the hash function. (The raw bits of the two keys
> are the same,
> but the fields are broken up differently.)
Use MAC function properly designed to prevent such attacks, such as HMAC
http://www.ietf.org/rfc/rfc2104.txt.
Best, Amir Herzberg
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