Re: [AVTCORE] Ben Campbell's Yes on draft-ietf-avtcore-aria-srtp-10: (with COMMENT)
Eric Rescorla <ekr@rtfm.com> Mon, 10 July 2017 12:41 UTC
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From: Eric Rescorla <ekr@rtfm.com>
Date: Mon, 10 Jul 2017 05:40:39 -0700
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To: Woo-Hwan Kim <whkim5@nsr.re.kr>
Cc: Ben Campbell <ben@nostrum.com>, The IESG <iesg@ietf.org>, avtcore-chairs@ietf.org, roni.even@mail01.huawei.com, draft-ietf-avtcore-aria-srtp@ietf.org, "avt@ietf.org" <avt@ietf.org>
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Subject: Re: [AVTCORE] Ben Campbell's Yes on draft-ietf-avtcore-aria-srtp-10: (with COMMENT)
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On Mon, Jul 10, 2017 at 2:30 AM, Woo-Hwan Kim <whkim5@nsr.re.kr> wrote: > Let me reply to the comment of Ben Campbell. > We would like to add the below to security considerations of the previous > draft(-10). > > -------------------------------------------------------------------- > As a note, at the time of publication of this document, SRTP > recommends HMAC-SHA1 as the default and mandatory-to-implement MAC > algorithm. So all of SRTP crypto suites except GCM based ones use > HMAC-SHA1 as their MAC algorithm to provide message authentication/ > integrity. Due to security concerns with SHA-1 [RFC6194], the IETF > is gradually moving away from SHA-1 and towards stronger hash > algorithms such as SHA-2 or SHA-3 families. For SRTP, however, SHA-1 > is only used in the calculation of an HMAC, and no security issue is > known in this case. To use a secure hash algorithm such as SHA-256 > in SRTP, the values of directly related SRTP parameters > auth_key_length and auth_tag_length should be determined considering > the overall security and efficiency when the crypto suite is applied. > I don't think this last sentence makes sense. We are moving towards AEAD algorithms, so I doubt we would ever want to publish <Cipher>-HMAC-SHA256. I would simply remove the sentence. -Ekr > > [RFC6194] Polk, T., Chen, L., Turner, S., and P. Hoffman, "Security > Considerations for the SHA-0 and SHA-1 Message-Digest > Algorithms", RFC 6194, DOI 10.17487/RFC6194, March 2011, > <http://www.rfc-editor.org/info/rfc6194>. > -------------------------------------------------------------------- > > Sincerely, Woo-Hwan Kim > > -----Original Message----- > From: Ben Campbell [mailto:ben@nostrum.com] > Sent: Saturday, July 08, 2017 5:33 AM > To: The IESG <iesg@ietf.org> > Cc: draft-ietf-avtcore-aria-srtp@ietf.org; avtcore-chairs@ietf.org; > roni.even@mail01.huawei.com; avt@ietf.org > Subject: Ben Campbell's Yes on draft-ietf-avtcore-aria-srtp-10: (with > COMMENT) > > Ben Campbell has entered the following ballot position for > draft-ietf-avtcore-aria-srtp-10: Yes > > When responding, please keep the subject line intact and reply to all > email addresses included in the To and CC lines. (Feel free to cut this > introductory paragraph, however.) > > > Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html > for more information about IESG DISCUSS and COMMENT positions. > > > The document, along with other ballot positions, can be found here: > https://datatracker.ietf.org/doc/draft-ietf-avtcore-aria-srtp/ > > > > ---------------------------------------------------------------------- > COMMENT: > ---------------------------------------------------------------------- > > I think it would be wise to add a paragraph to the security considerations > to call out the dependency on SHA1. A mention of what would need to happen > to migrate to newer hash functions could also be helpful. > > >
- [AVTCORE] Ben Campbell's Yes on draft-ietf-avtcor… Ben Campbell
- Re: [AVTCORE] Ben Campbell's Yes on draft-ietf-av… Woo-Hwan Kim
- Re: [AVTCORE] Ben Campbell's Yes on draft-ietf-av… Eric Rescorla
- Re: [AVTCORE] Ben Campbell's Yes on draft-ietf-av… Ben Campbell