Unknown Key-Share Attacks on DNS-based Authentications of Named Entities (DANE)

Unknown key-share attacks are a class of attacks that allow an attacker to deceive one peer of a secure communication as to the identity of the remote peer. When used with traditional, PKI-based authentication, TLS-based applications are generally safe from unknown key-share attacks. DNS-based Authentication of Named Entities (DANE), however, proposes that applications perform a different set of checks as part of authenticating a TLS connection. As a result, DANE as currently specified is likely to lead to unknown key-share attacks when clients support DANE for authentication. We describe these risks and some simple mitigations.