Subject: [AVTCORE] [Technical Errata Reported] RFC3711 (3712)

From: RFC Errata System <[email-masked]>
Date: Tue, 27 Aug 2013 04:14:28 -0700 (PDT)

The following errata report has been submitted for RFC3711,
"The Secure Real-time Transport Protocol (SRTP)".

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You may review the report below and at:
http://www.rfc-editor.org/errata_search.php?rfc=3711&eid=3712

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Type: Technical
Reported by: Christian S Oien <[email-masked]>

Section: 4.3.2

Original Text
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Replace the SRTP index by the 32-bit quantity: 0 || SRTCP index
(i.e., excluding the E-bit, replacing it with a fixed 0-bit), and use

Corrected Text
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Replace the SRTP index by the 48-bit quantity: 0 || SRTCP index
(i.e., excluding the E-bit, replacing it with a fixed 0-bit and then
prepending a 16-bits zero padding), and use

Notes
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Replacing with a 32-bit quantity means that the DIV operator will
yield a 32-bit quantity.  Following the specification of key_id for SRTCP
the <label> will have 32 bits to its right when XOR'ing with master_salt.

The majority of implementations, including libsrtp, invokes this XOR with the
<label> at the same position as for SRTP.  According to the specification
this should be done 16 bits to the right of this, when invoking for SRTCP.

Instructions:
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RFC3711 (draft-ietf-avt-srtp-09)
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Title               : The Secure Real-time Transport Protocol (SRTP)
Publication Date    : March 2004
Author(s)           : M. Baugher, D. McGrew, M. Naslund, E. Carrara, K. Norrman
Category            : PROPOSED STANDARD
Source              : Audio/Video Transport
Area                : Real-time Applications and Infrastructure
Stream              : IETF
Verifying Party     : IESG