[TLS] proposed text for draft-ietf-tls-dnssec-chain-extension-06
Paul Wouters <paul@nohats.ca> Wed, 21 March 2018 13:05 UTC
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Date: Wed, 21 Mar 2018 09:05:35 -0400
From: Paul Wouters <paul@nohats.ca>
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Subject: [TLS] proposed text for draft-ietf-tls-dnssec-chain-extension-06
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I think the below change would address my issue, without stepping on the things people brought up today (other then suggesting, not mandating, to send proof of non-existence when halting TLSA support in the zone) Paul diff --git a/draft-ietf-tls-dnssec-chain-extension-07.xml b/draft-ietf-tls-dnssec-chain-extension-07.xml index 333d2fc..0701b22 100644 --- a/draft-ietf-tls-dnssec-chain-extension-07.xml +++ b/draft-ietf-tls-dnssec-chain-extension-07.xml @@ -508,6 +508,15 @@ does not exceed the DNS TTLs or signature validity periods of the component records in the chain. </t> + <t> + If the zone using TLSA records stops using TLSA records, those TLS servers + that presented TLSA records using this extension SHOULD serve the authenticated + denial of existence of TLSA records for some time so their deployment remains + distinguishable from an attack. Ending the use of this extension SHOULD NOT be + done at the same time as changing the certificate being used on the server. This + helps clients from recognising that the current changed deployment is not + an attack performed using a different mis-issued PKIX certificate. + </t> </section> @@ -580,26 +588,14 @@ specific servers, clients could maintain a whitelist of sites where the use of this extension is forced. The client would refuse to authenticate such servers if they failed to deliver this extension. + Those clients should interpret authenticated denial of existence proofs + as valid use of this extension and continue to establish the TLS connection, + even if this connection uses a different PKIX certificate. Client applications could also employ a Trust on First Use (TOFU) like strategy, whereby they would record the fact that a server offered the extension and use that knowledge to require it for subsequent connections. </t> - <t> - This protocol currently provides no way for a server to prove that - it doesn't have a TLSA record. Hence absent whitelists, a client - misdirected to a server that has fraudulently acquired a public CA - issued certificate for the real server's name, could be induced to - establish a PKIX verified connection to the rogue server that precluded - DANE authentication. This could be solved by enhancing this protocol - to require that servers without TLSA records need to provide a DNSSEC - authentication chain that proves this (i.e. the chain includes NSEC or - NSEC3 records that demonstrate either the absence of the TLSA record, - or the absence of a secure delegation to the associated zone). Such an - enhancement would be impossible to deploy incrementally though since it - requires all TLS servers to support this protocol. - </t> - </section> <section title="Security Considerations">
- [TLS] proposed text for draft-ietf-tls-dnssec-cha… Paul Wouters
- Re: [TLS] proposed text for draft-ietf-tls-dnssec… Eric Rescorla