Re: Errata report on errata 2602 and 2120 on RFC 5479, "Requirements and Analysis of Media Security Management Protocols"
Cullen Jennings <fluffy <at> cisco.com>
2011-01-14 02:35:18 GMT
I agree with the Recommended status on these. Might be good to run the first one by EKR.
On Dec 13, 2010, at 3:09 PM, Worley, Dale R (Dale) wrote:
> ======================================================================
> RFC5479, "Requirements and Analysis of Media Security Management Protocols"
> Source of RFC: sip (rai)
>
> Errata ID: 2602
>
> Status: Reported
> Type: Technical
>
> Reported By: Fabio Pietrosanti
> Date Reported: 2010-11-04
>
> Section A.5.2 says:
>
> SDP Security Descriptions with SIPS
> Not applicable; SDP Security Descriptions does not have a long-
> term secret.
>
> It should say:
>
> SDP Security Descriptions with SIPS
> The PFS feature of SDP Security Description with SIPS rely on
> TLS and the availability or not of PFS for SRTP calls depends
> on the negotiated TLS key negotiation algorithm.
>
> If the selected TLS key negotiation algorithm of SIPS provide
> PFS feature, then the underlying SRTP encryption will support
> PFS. For example TLS_DHE_RSA_WITH_AES_256_CBC_SHA provde PFS
> feature as described in RFC5246. If the selected TLS key
> negotiation algorithm of SIPS does not provide PFS feature,
> then the underlying SRTP encryption will not support PFS.
> For example TLS_RSA_WITH_AES_256_CBC_SHA does not provide PFS
> feature as described in RFC5246.
>
>
> Notes:
>
> It's not true that SDP Security Descriptions with SIPS have PFS "Not
> applicable" because the SDES rely on TLS that is part of the security
> scheme.
>
> Practically if the long terms keys (the x509v3 RSA key of SIPS server)
> is compromised, the TLS sessions can be decrypted, the SDES key
> extracted and SRTP calls deciphered.
>
> TLS support key exchange methods that provide PFS trough the use of
> Ephemeral Diffie Hellman keys.
>
> When SIPS use TLS with DHE key negotiation, then SDES acquire PFS
> feature because even in case of long-term key compromise (the server
> x509v3 RSA key), the short term keys (the SDES keys exchanged) will be
> safe.
> ----------------------------------------------------------------------
> Recommended status: (correct) Verified (publish)
> Should be reviewed by a security expert.
>
> It seems that the entry for "SDP Security Descriptions with S/MIME" is
> also incorrect, as revelation of the private keys of the participants
> will render the SDES readable. I think better phrasing of the revised
> wording is:
>
> SDP Security Descriptions with SIPS
> PFS if the selected TLS cipher suites for the SIPS hops provide PFS.
>
> SDP Security Descriptions with S/MIME
> No PFS.
>
> This needs to be reviewed by a security expert.
> ======================================================================
> RFC5479, "Requirements and Analysis of Media Security Management Protocols"
> Source of RFC: sip (rai)
>
> Errata ID: 2120
>
> Status: Reported
> Type: Editorial
>
> Reported By: Alfred Hoenes
> Date Reported: 2010-04-05
>
> Section 4.4,3rd para says:
>
> | A typical case of using media security where two entities are having
> a Voice over IP (VoIP) conversation over IP-capable networks.
> [...]
>
> It should say:
>
> | A typical case of using media security is where two entities are
> having a Voice over IP (VoIP) conversation over IP-capable networks.
> [...]
>
> Notes:
>
> Rationale: missing verb.
> ----------------------------------------------------------------------
> Recommended status: (correct) Hold for document update
> ======================================================================
>
> Dale
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