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visits member for 1 year, 10 months
seen Jun 19 at 19:08

Jan
9
comment Using CBC with a fixed IV and a random first plaintext block
So then I am to understand that when you refer to being unable to predict the IV, that you mean that the first ciphertext block, whose plaintext is xor'd with the incrementing IV (or whatever), is sufficiently unpredictable between encryption runs, not that the IV used is sufficiently unpredictable? As it stands, if I were to pass the (incrementing) IV used in clear text along with the ciphertext, an eve would be able to see that the IV is clearly predictable, but the resulting first block still is not.
Jan
9
comment Using CBC with a fixed IV and a random first plaintext block
How is the IV unpredictable if I'm combining all zeros with a message counter?
Jan
8
comment Using CBC with a fixed IV and a random first plaintext block
I guess its supposed to save on sending the IV out the door, but that the unnecessary calls to the encryption/decryption routines may be unacceptably wasteful
Jan
7
awarded  Student
Jan
7
asked Why not use CBC, not send IV, and assume first plaintext block is garbage?