Re: [TLS] TLS specification clarification in case of client authentication: different CA with DN different only in case
devzero2000writes: > Hello everyone > > >From the tls 1.2 specification, speaking of client authentication, > https://tools.ietf.org/html/rfc5246#section-7.4.4 par 7.4.4 (but it is the > same for the last tls draft 1.3 par. 4.2.4.) > > when he says: > > certificate_authorities > A list of the distinguished names [X501] of acceptable > certificate_authorities, represented in DER-encoded format. > > What would be the right behavior if the server has the certificates of two > different CAs (different subject key info, public key parameter) but whose > subject DN differs only for the case (for example > something like this > > Subject: /C=US/ST=California/L=Mountain View/O=XXX Inc/CN=mail.xxx.com > > and > > > Subject: /C=US/ST=California/L=mountain View/O=XXX Inc/CN=mail.xxx.com These are the same distinguished name under RFC 5280 section 7.1, although in practice implementations may treat them as different, most notably under the older RFC 3280 rules. I believe the correct behaviour is to Not Do That---do not generate certificates which have distinguished names that match under RFC 5280 and are not byte-for-byte identical in DER format, if you must do that make sure they are not valid at the same time, and if you must do that, try to ensure no piece of software is aware of both of them, and if you must do that, don't be surprised if the behaviour is inconsistent and especially don't be surprised if the LDAP StringPrep rules are not implemented correctly or at all. And if you value your sanity, don't rely on anything that might change if the Unicode standard is revised. However, the TLS specification doesn't say that the list must contain each DN only once. So in this situation I would suggest the software should list both. Indeed I would recommend listing every distinct DER representation that's present in any acceptable certificate. ___ TLS mailing list TLS@ietf.org https://www.ietf.org/mailman/listinfo/tls
[TLS] TLS specification clarification in case of client authentication: different CA with DN different only in case
Hello everyone >From the tls 1.2 specification, speaking of client authentication, https://tools.ietf.org/html/rfc5246#section-7.4.4 par 7.4.4 (but it is the same for the last tls draft 1.3 par. 4.2.4.) when he says: certificate_authorities A list of the distinguished names [X501] of acceptable certificate_authorities, represented in DER-encoded format. What would be the right behavior if the server has the certificates of two different CAs (different subject key info, public key parameter) but whose subject DN differs only for the case (for example something like this Subject: /C=US/ST=California/L=Mountain View/O=XXX Inc/CN=mail.xxx.com and Subject: /C=US/ST=California/L=mountain View/O=XXX Inc/CN=mail.xxx.com Note the different (M|m)ountain ) 1 - In one case the server could send both DNs to the client, the client could choose the one that signed its certificate, and the server would be able to validate, based on the autority key identier, the client with the right CA. 2 - In another case, instead, the server chooses to send only one of the two DNs, probably the first configured, and if that is not the one that signed the client certificate, the authentication would not continue. I have seen that some TLS implementations follow both of the behaviors described and this creates interoperability issues, i think. It should not be an ambiguous behavior, and it should be clarified. Opinions ? Thanks you very much for the attention Ciao Elia ___ TLS mailing list TLS@ietf.org https://www.ietf.org/mailman/listinfo/tls