Composition Theorems for CryptoVerif and Application to TLS 1.3

Bruno Blanchet (1)

1 PROSECCO - Programming securely with cryptography

We present composition theorems for security protocols , to compose a key exchange protocol and a symmetric-key protocol that uses the exchanged key. Our results rely on the computational model of cryptography and are stated in the framework of the tool CryptoVerif. They support key exchange protocols that guarantee injective or non-injective authentication. They also allow random oracles shared between the composed protocols. To our knowledge, they are the first composition theorems for key exchange stated for a computational protocol verification tool, and also the first to allow such flexibility. As a case study, we apply our composition theorems to a proof of TLS 1.3 Draft-18. This work fills a gap in a previous paper that informally claims a compositional proof of TLS 1.3, without formally justifying it.

Domaines: Cryptographie et sécurité [cs.CR]

Bruno Blanchet. Composition Theorems for CryptoVerif and Application to TLS 1.3. 31st IEEE Computer Security Foundations Symposium (CSF'18), Jul 2018, Oxford, United Kingdom. ⟨10.1109/CSF.2018.00009⟩. ⟨hal-01947959⟩