[Cfrg] Re: [saag] KDF: Randomness extraction vs. key expansion
Nicolas Williams <Nicolas.Williams@sun.com> Sat, 29 October 2005 08:08 UTC
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Date: Sat, 29 Oct 2005 03:08:31 -0500
From: Nicolas Williams <Nicolas.Williams@sun.com>
To: canetti <canetti@watson.ibm.com>
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Cc: saag@mit.edu, cfrg@ietf.org
Subject: [Cfrg] Re: [saag] KDF: Randomness extraction vs. key expansion
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On Fri, Oct 28, 2005 at 03:48:59PM -0400, canetti wrote: > Finally, a general remark on modeling and abstractions: I can imagine people > read this note and think to themselves: "why is he bothing us with these > abstract notions. In the end of the day all that is going to be done is a > bunch of hashes and/or block cipher operations, so why not do it explicitly > and be done with it." My answer is that these abstractions are our > only hope to make sense of this spaghetti of hashes, shifts, > concatenations, exponentiations etc. If we want to build systems that will > have some pretence of security we have no choice but use the abstractions > and abide by them, even is there is some price in complexity. I'm with you on the same layering abstraction matter; even we agreed on the identity function for randomness extraction there would still be a layering abstraction. This KDF has a lot of inputs, and in some ways arguably not enough (e.g., IDs but, surprisingly, no ID types), but a PRF has a much simpler function signature. So it seems simpler to define a PRF and then a KDF in terms of said PRF than to inextricably mix the two. And why shouldn't there be a standard PRF if there is to be a standard KDF? And if there's to be a standard PRF then that'd be all the more reason to base a standard KDF on a standard PRF. Nico -- _______________________________________________ Cfrg mailing list Cfrg@ietf.org https://www1.ietf.org/mailman/listinfo/cfrg
- [Cfrg] KDF: Randomness extraction vs. key expansi… canetti
- [Cfrg] KDF: Randomness extraction vs. key expansi… David Wagner
- [Cfrg] On using ROs for analyzing randomness extr… canetti
- [Cfrg] Re: [saag] KDF: Randomness extraction vs. … Bill Sommerfeld
- Re: [Cfrg] KDF: Randomness extraction vs. key exp… canetti
- [Cfrg] KDF: Randomness extraction vs. key expansi… David Wagner
- [Cfrg] Re: [saag] KDF: Randomness extraction vs. … canetti
- [Cfrg] Re: [saag] KDF: Randomness extraction vs. … Nicolas Williams
- Re: [Cfrg] KDF: Randomness extraction vs. key exp… D. J. Bernstein
- Re: [saag] Re: [Cfrg] KDF: Randomness extraction … canetti
- Re: [saag] Re: [Cfrg] KDF: Randomness extraction … D. J. Bernstein
- Re: [saag] Re: [Cfrg] KDF: Randomness extraction … canetti