AES-128 keys unique for fixed plaintext/ciphertext pair?

Dave Howe DaveHowe at
Fri Feb 21 19:25:09 EST 2003

Hmm. another simpler theory to remove Shannon from the discussion.

assume that the original assertion is correct - that for each plaintext p
and each cyphertext c there exists only one key k that is valid to map
encrypt(p,k)=c. In this case, for each possible cyphertext c, *every*
possible plaintext p is a valid translation given a unique key k. for that
reason, the uniary distance for encrypt() must be larger than one block - as
it is self evidently not possible to map *any* c to a unique p without
knowledge of the key.
For that reason, Shannon cannot be applied to a single block of encrypt(),
and can be safely ignored :)

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