From f7dd23790a13b3f4544817df5bb0d655f88b709d Mon Sep 17 00:00:00 2001 From: "Matthew A. Miller" Date: Mon, 23 Mar 2015 13:22:01 -0500 Subject: [PATCH] XEP-0344 v0.3 -- Described same-certificate flow. --- xep-0344.xml | 132 ++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 125 insertions(+), 7 deletions(-) diff --git a/xep-0344.xml b/xep-0344.xml index daa9262e..d006c380 100644 --- a/xep-0344.xml +++ b/xep-0344.xml @@ -21,6 +21,14 @@ dwd + + 0.3 + 2015-03-23 + dwd/ph + +

Described same-certificate flow.

+ + 0.2 2014-03-19 @@ -68,7 +76,7 @@

This document will tell a tale of two servers; orchard.capulet.example is trying to contact home.montague.example. Each server operates a single domain; these are capulet.example and montague.example respectively.

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The traditional pattern is shown here:

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This traditional pattern involves the following protocol exchanges when dialback over TLS is used:

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The Receiving Server may need to establish a connection to the Authoritative Server at this point.

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This traditional pattern involves the following protocol exchanges when dialback over TLS is used:

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If during the initial connection, the Receiving Server is unable to determine that the certificate presented is trustworthy but the Authoritative Server presents the same certificate as the Originating Server, the <db:verify/> step can be elided.

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Note: the Receiving Server MUST still check that the hostname in the certificate matches.

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Essentially, this replaces the Dialback Key Validation step from &xep0185; with the somewhat more elaborate proof of posession of the private key associated with the certificate.

+ | + | (ID D60000229F) | + | | + | send | capulet.example + | dialback key | (as Authoritative + | -----(STEP 1)----> | Server) + | | ----------------- + | | [if necessary, | + | | perform DNS | + | | lookup on | + | | Sender Domain, | + | | open TCP | + | | connection, | + | | and establish | + | | stream] | + | | -----------------> | + | | [observe certificate is for + | | capulet.example and same as + | | used by orchard.capulat.example] + | report | + | dialback result | + | <-----(STEP 4)---- | + ]]> + + +

This pattern involves the following protocol exchanges:

+ + ]]> + + + + + + + ]]> + + ]]> + + ]]> + + ]]> + + + + + + ]]> + + b4835385f37fe2895af6c196b59097b16862406db80559900d96bf6fa7d23df3 + + ]]> +

The Receiving Server may need to establish a connection to the Authoritative Server at this point. Here we assume that this connection is using TLS and the certificate presented by the Authoritative Server is the same as the one used by the Originating Server and contains the domain name claimed by the Originating Server.

+ + ]]> +

With respect to XEP-0220's security considerations, the adaptations in this document add at minimum channel encryption and integrity, which forces an attacker into making an active attack, rather than passive eavesdropping. This raises the cost of an attack significantly. However, unless the certificates are authenticated, there is still a man-in-the-middle attack possible, and the reliance on unauthenticated DNS remains problematic.

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Use of the "Same Certificate" shortcut described in XXXX is not thought to materially alter the security profile beyond that described above. In particular, it does not alter the level of trust an implementation may put in authentication.

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Use of the "Dialback without dialback" shortcut described in XXXX raises the level of authentication to that of the TLS/SASL-EXTERNAL process described in RFC 6120, and is thought to be indistinguishable from a security standpoint. As such, the security considerations relating to this in RFC 6120 et al apply.

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Use of the "Dialback without dialback" shortcut described in section 2.4 raises the level of authentication to that of the TLS/SASL-EXTERNAL process described in RFC 6120, and is thought to be indistinguishable from a security standpoint. As such, the security considerations relating to this in RFC 6120 et al apply.

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Use of the "Same Certificate" shortcut described in section 2.6 is not thought to materially alter the security profile beyond that described above. In particular, it does not alter the level of trust an implementation may put in authentication.

If both SRV and A/AAAA records are protected by DNSSEC, this means that the correct address for the peer can be proven, removing DNS forgery as an attack vector. Without TLS, it is however still possible to mount an array of attacks, including IP spoofing and eavesdropping.