A comparison of different variants of the Canetti-Krawczyk model can be found in . Popular examples of such protocols are MQV , HMQV , SMQV , KEA , and NAXOS . This family of security models is especially suited to protocols with only two message exchanges, with one-round key exchange protocols constituting the most important subclass. In this paper, we use a variant of the Canetti-Krawczyk security model. However, their construction is currently mainly of conceptual interest, as it is not yet efficient enough to be deployed at large scale in practice.
Sigma client 2.0 leak full#
extended the “puncturable encryption”-approach of Green and Miers to show that even 0-RTT KE with full forward secrecy is possible, by evolving the secret key after each decryption. Zhao considers identity-concealed 0-RTT protocols, where user privacy is protected by hiding identities of users in a setting with mutual cryptographic authentication of both communicating parties. They describe a security model which is bespoke to QUIC, adopting the complex, monolithic security model of to the protocol’s requirements. gave an alternate analysis of QUIC, which considers both efficiency and security. There are no foundational constructions as yet, and the relation to other cryptographic protocols and primitives is not yet well-understood.Īt ACM CCS 2014, Fischlin and Günther provided a formal definition of multi-stage key exchange protocols and used it to analyze the security of QUIC. All previous works on 0-RTT KE conducted a-posteriori security analyses of the QUIC protocol, with tailored models. The concept of 0-RTT key exchange was not developed in academia, but in industry – motivated by concrete practical demands of distributed applications. Therefore QUIC does not provide strong key independence in the sense sketched above. It only shows that the authenticity of the server’s Diffie-Hellman share, which is sent in QUIC to establish \(k_2\), depends strongly on the security of key \(k_1\). Note that this theoretical attack does not imply that QUIC is insecure. See for more details on key dependency in QUIC. 1) achieves low-latency by caching a signed server configuration file on the client side, which contains a medium-lived Diffie-Hellman (DH) share \(Y_0=g^\) query. LLKE, zero-RTT or 0-RTT key exchange) was opened when Google proposed the QUIC protocol. Fundamentally, the discussion on low-latency key exchange (aka. This was soon realized to be problematic, and in IKEv2 the number of RTTs was reduced to 2. Similarly, the older IPSec IKE version v1 needs between 3 RTT (aggressive mode + quick mode) and 4.5 RTT (main mode + quick mode). With the increased use of encryption, Footnote 1 efficiency is of escalating importance for protocols like TLS.
Basically, the first generation of internet key exchange protocols did not care too much about efficiency, since secure connections were considered to be the exception rather than the rule: SSL (versions 2.0 and 3.0) and TLS (versions 1.0, 1.1, and 1.2) require 2 round-trip times (RTT) for key establishment before the first cryptographically-protected payload data can be sent. KeywordsĮfficiency, in terms of messages to be exchanged before a key is established, is a growing consideration for internet protocols today. We also give the first constructions of 0-RTT KE which are provably secure in these models, based on the generic assumption that secure non-interactive key exchange (NIKE) exists (This work was partially supported by a STSM Grant from COST Action IC1306). We call this property strong key independence. second) key should remain indistinguishable from a random value, even if the second (resp. In this paper, we propose simple security models, which catch the intuition behind known 0-RTT KE protocols namely that the first (resp. The second key is computed using an ephemeral server share and the same ephemeral client share. The first key is a combination of an ephemeral client share and a long-lived server share. In 0-RTT KE two keys are generated, typically using a Diffie-Hellman key exchange. The 0-RTT KE concept was first realized by Google in the QUIC Crypto protocol, and a 0-RTT mode has been intensively discussed for inclusion in TLS 1.3. Zero Round-Trip Time (0-RTT) key exchange protocols allow for the transmission of cryptographically protected payload data without requiring the prior exchange of messages of a cryptographic key exchange protocol.
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