Subject: [smime] [Technical Errata Reported] RFC2631 (2506)

From: RFC Errata System <[email-masked]>
Date: Wed, 1 Sep 2010 05:30:49 -0700 (PDT)

The following errata report has been submitted for RFC2631,
"Diffie-Hellman Key Agreement Method".

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You may review the report below and at:
http://www.rfc-editor.org/errata_search.php?rfc=2631&eid=2506

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Type: Technical
Reported by: Yves Legrandgerard <[email-masked]>

Section: 2.2.1.1

Original Text
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6. For i = 0 to m' - 1

        U = U + (SHA1[SEED + i] XOR SHA1[(SEED + m' + i)) * 2^(160 * i)

   Note that for m=160, this reduces to the algorithm of [FIPS-186]

        U = SHA1[SEED] XOR SHA1[(SEED+1) mod 2^160 ].

Corrected Text
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6. For i = 0 to m' - 1

        U = U + (SHA1[SEED + i] XOR SHA1[(SEED + m' + i) mod 2^(160 * (i + 1))])

   Note that for m=160, this reduces to the algorithm of [FIPS-186]

        U = SHA1[SEED] XOR SHA1[(SEED + 1) mod 2^160].

Notes
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The line:
  U = U + (SHA1[SEED + i] XOR SHA1[(SEED + m' + i)) * 2^(160 * i)
is syntactically incorrect. Closing bracket of last 'SHA1[' is missing.
Moreover, when m=160 (m'=1), the loop cannot reduce to the line:
  U = SHA1[SEED] XOR SHA1[(SEED + 1) mod 2^160]
as it can be easily seen.

Instructions:
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RFC2631 (draft-ietf-smime-x942-07)
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Title               : Diffie-Hellman Key Agreement Method
Publication Date    : June 1999
Author(s)           : E. Rescorla
Category            : PROPOSED STANDARD
Source              : S/MIME Mail Security
Area                : Security
Stream              : IETF
Verifying Party     : IESG