Re: [TLS] Verifying X.509 Certificate Chains out of order
pgut001@cs.auckland.ac.nz (Peter Gutmann) Tue, 07 October 2008 03:26 UTC
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From: pgut001@cs.auckland.ac.nz
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Date: Tue, 07 Oct 2008 16:27:22 +1300
Cc: tls@ietf.org
Subject: Re: [TLS] Verifying X.509 Certificate Chains out of order
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Martin Rex <Martin.Rex@sap.com> writes: >Looking at the official protocol spec, the possibility to send an empty list >of certificate_authorities in the CertificateRequest message was introduced >as a purely optional feature with TLS v1.1. It was _NOT_ previously allowed >to send an empty list in the SSL v3 and TLS v1.0 specifications! Yes it is. The minimum length 3 can be used to encode a zero-length ASN.1 SEQUENCE (using BER encoding), there's nothing there that says it has to contain anything. I've been sending this in my certRequest for, oh, about 10 years now without running into any problems. (Having said that, since client certs are so rarely used if there were problems it's unlikely you'd ever see them, but in any case it's worked fine so far). >I think it is a pretty dumb engineering decision to create an implementation >of SSL/TLS where it is possible to configure the Server to request a client >Certificate and NO MEANS to configure the list of certificate_authorities for >the ClientRequest message Why? The reason I never bothered to implement this is because I can't see any use for it, if a server asks for a cert from the client then the client will either use whatever cert it has for that server or respond "no-cert". Even in the unlikely situation that the client has multiple certs all intended for SSL client auth (most users have zero certs for SSL client auth), unless every one of them is specially chosen to be from a different CA then specifying the CA name will have the same effect as specifying no CA name. All this does is add uneccessary complexity (both to the implementation itself and for the user who has to configure it and deal with the results) and increase the attack surface. If I was able to identify a good purpose for it (SSH uses exactly the same auth mechanism and gets by just fine without it) *and* if any user ever asked for it I'd think about adding support for it, but until then I've left it (along with a zillion other often-incomprehensible bits and pieces in standards) as a TODO. Peter. _______________________________________________ TLS mailing list TLS@ietf.org https://www.ietf.org/mailman/listinfo/tls
- [TLS] Verifying X.509 Certificate Chains out of o… Simon Josefsson
- Re: [TLS] Verifying X.509 Certificate Chains out … Peter Gutmann
- Re: [TLS] Verifying X.509 Certificate Chains out … Rob Dugal
- Re: [TLS] Verifying X.509 Certificate Chains out … Dr Stephen Henson
- Re: [TLS] Verifying X.509 Certificate Chains out … Peter Gutmann
- Re: [TLS] Verifying X.509 Certificate Chains out … Eric Rescorla
- Re: [TLS] Verifying X.509 Certificate Chains out … Steven M. Bellovin
- Re: [TLS] Verifying X.509 Certificate Chains out … Martin Rex
- Re: [TLS] Verifying X.509 Certificate Chains out … Martin Rex
- Re: [TLS] Verifying X.509 Certificate Chains out … Mike
- Re: [TLS] Verifying X.509 Certificate Chains out … Peter Gutmann
- Re: [TLS] Verifying X.509 Certificate Chains out … Peter Gutmann
- Re: [TLS] Verifying X.509 Certificate Chains out … Stefan Santesson
- Re: [TLS] Verifying X.509 Certificate Chains out … Martin Rex
- Re: [TLS] Verifying X.509 Certificate Chains out … Axel.Heider
- Re: [TLS] Verifying X.509 Certificate Chains out … Martin Rex
- Re: [TLS] Verifying X.509 Certificate Chains out … Martin Rex
- Re: [TLS] Verifying X.509 Certificate Chains out … Martin Rex
- Re: [TLS] Verifying X.509 Certificate Chains out … Peter Gutmann
- Re: [TLS] Verifying X.509 Certificate Chains out … Alexander Klink
- Re: [TLS] Verifying X.509 Certificate Chains out … Eric Rescorla
- Re: [TLS] Verifying X.509 Certificate Chains out … Martin Rex
- Re: [TLS] Verifying X.509 Certificate Chains out … Peter Gutmann
- Re: [TLS] Verifying X.509 Certificate Chains out … Peter Sylvester
- Re: [TLS] Verifying X.509 Certificate Chains out … Eric Rescorla
- Re: [TLS] Verifying X.509 Certificate Chains out … Martin Rex
- Re: [TLS] Verifying X.509 Certificate Chains out … Peter Sylvester
- Re: [TLS] Verifying X.509 Certificate Chains out … Stefan Santesson
- Re: [TLS] Verifying X.509 Certificate Chains out … Martin Rex
- Re: [TLS] Verifying X.509 Certificate Chains out … Stefan Santesson
- Re: [TLS] Verifying X.509 Certificate Chains out … Peter Gutmann
- Re: [TLS] Verifying X.509 Certificate Chains out … Steven M. Bellovin
- [TLS] Antwort: Re: Verifying X.509 Certificate Ch… Axel.Heider
- Re: [TLS] Verifying X.509 Certificate Chains out … Martin Rex
- Re: [TLS] Verifying X.509 Certificate Chains out … Nelson B Bolyard
- Re: [TLS] Verifying X.509 Certificate Chains out … Peter Gutmann
- Re: [TLS] Verifying X.509 Certificate Chains out … Ben Laurie
- Re: [TLS] Verifying X.509 Certificate Chains out … Ben Laurie
- Re: [TLS] Verifying X.509 Certificate Chains out … Jeffrey A. Williams
- Re: [TLS] Verifying X.509 Certificate Chains out … Martin Rex
- Re: [TLS] Verifying X.509 Certificate Chains out … Nelson B Bolyard
- Re: [TLS] Verifying X.509 Certificate Chains out … Peter Gutmann
- Re: [TLS] Verifying X.509 Certificate Chains out … Nelson B Bolyard
- Re: [TLS] Verifying X.509 Certificate Chains out … Peter Gutmann
- Re: [TLS] Verifying X.509 Certificate Chains out … Simon Josefsson
- Re: [TLS] Verifying X.509 Certificate Chains out … Peter Gutmann
- Re: [TLS] Verifying X.509 Certificate Chains out … Yoav Nir
- Re: [TLS] Verifying X.509 Certificate Chains out … Peter Gutmann
- Re: [TLS] Verifying X.509 Certificate Chains out … Nelson B Bolyard
- Re: [TLS] Verifying X.509 Certificate Chains out … Peter Gutmann
- Re: [TLS] Verifying X.509 Certificate Chains out … Alexander Klink