Re: [TLS] Issue 49: Finished.verify length
Bodo Moeller <bmoeller@acm.org> Fri, 14 September 2007 12:13 UTC
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Date: Fri, 14 Sep 2007 14:13:50 +0200
From: Bodo Moeller <bmoeller@acm.org>
To: Pasi.Eronen@nokia.com
Subject: Re: [TLS] Issue 49: Finished.verify length
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On Fri, Sep 14, 2007 at 02:03:10PM +0200, Bodo Moeller wrote: >>> But you don't need a very long verify_data. We also don't need >>> very long record-layer MACs. Both are needed only for real-time >>> authentication, which cannot be attacked after the fact. >> This is true; but reasonable people seem to have different opinions >> on what exactly is "sufficiently long". For example, RFC 4106 specifies >> three different choices for ICV (MAC) length (128/192/256 bits). > IPsec is a different setting since it is not based on streams (which > would be aborted in case of a decryption error). However, this > reminds me to take DTLS into account, so yes, we possibly might need > long record-layer MACs (just for consistency for DTLS, not for actual > TLS security reasons). > > Of course, the Finished message payload (verify_data) still will have > to be processed just once. (An incorrect record-layer MAC is just a > reason to discard this particular packet in DTLS, but if the > record-layer MAC is correct and the verify_data isn't, then this > is a very bad sign, and the session should be canceled.) Oops, I forgot to make explicit what follows from this --: While longer MACs makes sense for protocols such as IPsec and DTLS, this doesn't mean that we have a similar reason to use longer verify_data fields with DTLS. Bodo _______________________________________________ TLS mailing list TLS@lists.ietf.org https://www1.ietf.org/mailman/listinfo/tls
- [TLS] Issue 49: Finished.verify length Eric Rescorla
- Re: [TLS] Issue 49: Finished.verify length Mike
- Re: [TLS] Issue 49: Finished.verify length Eric Rescorla
- Re: [TLS] Issue 49: Finished.verify length Mike
- Re: [TLS] Issue 49: Finished.verify length Bodo Moeller
- RE: [TLS] Issue 49: Finished.verify length Pasi.Eronen
- Re: [TLS] Issue 49: Finished.verify length Bodo Moeller
- Re: [TLS] Issue 49: Finished.verify length Bodo Moeller
- RE: [TLS] Issue 49: Finished.verify length Pasi.Eronen
- Re: [TLS] Issue 49: Finished.verify length Eric Rescorla
- Re: [TLS] Issue 49: Finished.verify length Eric Rescorla
- RE: [TLS] Issue 49: Finished.verify length Pasi.Eronen
- Re: [TLS] Issue 49: Finished.verify length Eric Rescorla
- RE: [TLS] Issue 49: Finished.verify length Pasi.Eronen
- Re: [TLS] Issue 49: Finished.verify length Eric Rescorla
- RE: [TLS] Issue 49: Finished.verify length Pasi.Eronen
- Re: [TLS] Issue 49: Finished.verify length Russ Housley