Encrypting block driver for Linux...need some advice
Andy Brown
asb at nexor.co.uk
Thu Jul 27 02:44:49 PDT 1995
On Wed, 26 Jul 1995, Johnathan Corgan wrote:
> Another, more crypto related question--how to deal with IV's? Right now,
> I'm using 512 byte sectors with CBC. For each sector, the IV is the
> sector number. This frustrates the known plaintext attack issue, but I'm
> not sure if such a simple scheme is really effective. Probably not.
Your scheme should be OK. If you'd chosen the same IV for each sector
then identical sectors would encrypt the same. If I remember rightly
then having a known IV only affects the security of the first block,
after that the ciphertext chaining comes into effect.
- Andy
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