Re: Size of IV field in DES-CBC mode

[Phil Karn <karn@unix.ka9q.ampr.org>]

>4 bytes will do, but for CBC mode, some sort of expansion (e.g. CRC-32) to
>64 bits would be nice just to make sure.

Or perhaps just repeating the 4 bytes to make 8? It's sufficient to ensure
that the XOR of the IV and the first block of plaintext always differs
in at least one bit.

Phil

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References:

• Re: Size of IV field in DES-CBC mode
• From: colin@nyx10.cs.du.edu (Colin Plumb)

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