In message <[EMAIL PROTECTED]> on Thu, 26 Jun 2003 13:31:37 -0700, Michael Sierchio
<[EMAIL PROTECTED]> said:
kudzu> Richard Levitte - VMS Whacker wrote:
kudzu>
kudzu> > OK, I've been follownig this discussion for a while, and it's time I
kudzu> > ake action. Basically, to provide for all the current and future ways
kudzu> > of handling the IV, I can see three alternatives:
kudzu> >
kudzu> > - have the application provide a function that manipulates the IV.
kudzu> > - have the application specify exactly which part of the IV is the
kudzu> > actual counter (in bit positions, or would byte positions be
kudzu> > enough?).
kudzu> > - a combination of the two (that would make our code extract the
kudzu> > counters bits and only give those to the provided function, which
kudzu> > then does the increment in any way it wishes).
kudzu>
kudzu> There's no need for an IV for SSL/TLS encryption with AES CTR mode.
kudzu> All that's needed is a counter, and a mechanism to prevent using
kudzu> more than 2^38 or so bytes of keystream without changing the key.
Whatever, I used the terms like this:
- IV is a bitstring of some sort (possibly random), of the same size
as the crypto algorithm block. In the AES case, it would be 128
bits.
- For CTR mode, the counter is a part of the IV. The rest of the IV
is some kind of random bits (a nonce).
Those are the conditions I'm working from. Makes sense?
kudzu> > lee_dilkie> (the other thing to remember is that CTR can be used with
kudzu> > lee_dilkie> any block cipher, it's not limited to AES)
kudzu> >
kudzu> > Absolutely.
kudzu>
kudzu> Not quite. You want to be sure to use block ciphers that are
kudzu> differentially strong. AES is particularly well-suited.
Point.
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