[Cfrg] Security analysis of draft-smyshlyaev-re-keying-00.txt
Watson Ladd <watsonbladd@gmail.com> Mon, 07 November 2016 17:58 UTC
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From: Watson Ladd <watsonbladd@gmail.com>
Date: Mon, 07 Nov 2016 09:58:05 -0800
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Subject: [Cfrg] Security analysis of draft-smyshlyaev-re-keying-00.txt
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Dear all, draft-smyshlyaev-re-keying-00.txt fails to achieve its stated security goals, for fairly trivial reasons. Draft-smyshlyaev-re-keying-00 uses the same value of H for the entire message. The authenticity bounds for GCM depend on the length of the message, not the number of blocks encrypted with the same key. Therefore this bounds are not improved by the rekeying mechanism proposed. The probability of forgery is L/2^{-128} where L is the length of the message, and therefore we do not have beyond-birthday bound security with this proposed mechanism. Sincerely, Watson Ladd
- [Cfrg] Security analysis of draft-smyshlyaev-re-k… Watson Ladd
- Re: [Cfrg] Security analysis of draft-smyshlyaev-… Stanislav V. Smyshlyaev