Re: encryption question


"Henrick Hellström" <henrick@xxxxxxxxxxxx> wrote in message
That might be an extremely bad idea if not done correctly:

Setup:
1. Select password P
2. Store H = Hash(P)
3. Store C = E(Hash(P),T)

Decryption
1. User inputs P'
2. If H <> Hash(P') return Error
3. Return T = E(Hash(P),C)

The flaw in this scheme ought to be fairly obvious. An attacker who finds
a H,C pair might simply calculate T = E(H,C) and be done with it, without
any information whatsoever about P.

Thanks for the input. I imply from your comment that using the hash function
method will work fine for symmetrical encryption.

Rael


.

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