RE: [TLS] Truncated HMAC recommendation

"Whyte, William" <WWhyte@ntru.com> Mon, 27 November 2006 19:40 UTC

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Subject: RE: [TLS] Truncated HMAC recommendation
Date: Mon, 27 Nov 2006 14:39:03 -0500
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From: "Whyte, William" <WWhyte@ntru.com>
To: "Blumenthal, Uri" <uri.blumenthal@intel.com>, Mike <mike-list@pobox.com>, tls@ietf.org
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> *I* would want to truncate the MAC to make cryptanalytic job of my
> adversary harder by forbidding him verification of his guesses of the
> correct authentication key (as I do not provide the entire computed
> MAC).

But if you truncate it to half-length, two MACs are enough to allow
verification of a guess with high probability. I don't think this
is a significant gain.

William

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