Description
Providing security proofs instead of arguing lack of existing relevant attacks is a quite new approach when it comes to cryptography. In the last thirty years, a lot of work has been done to formalize security of systems and prove of the achievement of security criteria. It has resulted in the design of a great number of proofs under various hypotheses. Though a step in the right direction, these pencil-and-paper proofs are so numerous, involved and technical that the community has difficulty to carefully check them. The well-known example of the encryption scheme OAEP whose security proof, apparently correct, was corrected seven years after its publication illustrates that security-dedicated verification tools need to be designed. Our work takes place in the so-called computational model, where messages are considered to be bitstrings, and system adversaries are probabilistic Turing machines. A proof of security is then a complexity-theoretic reduction argument: the probability of success of an adversary in solving a security challenge is reduced to its ability to solve a known difficult problem (given a fixed amount of resources). Firstly, we provide some intuition on usual security requirements, and common sketches of security proofs. Then, we present a semantics and a logic to formalize security proofs. One could say there are several levels in automatic proving: computer-aided verification of proofs, computer-aided design of proofs, and automatic generation of proofs. We show how our inference rules can be used to derive proofs and verify them automatically, or sometimes perform a proof search using some additional inputs.
Prochains exposés
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Key Attack on the ACDGV Matrix Encryption Scheme
Orateur : Anmoal Porwal - Technical University of Munich
I will present our key-recovery attack on the ACDGV public-key encryption scheme proposed at ASIACRYPT 2024 by Aragon, Couvreur, Dyseryn, Gaborit, and Vinçotte. The secret key is a Gabidulin code hidden by appending random rows and columns and by left- and right-multiplication with invertible matrices. Our attack exploits the resulting algebraic structure to recover an equivalent secret key. It[…]-
Cryptography
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Asymmetric primitive
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Module Learning With Errors and Structured Extrapolated Dihedral Cosets
Orateur : Jinwei Zheng - Télécom Paris
The Module Learning With Errors (MLWE) problem is the fundamental hardness assumption underlying the key encapsulation and signature schemes ML-KEM and ML-DSA, which have been selected by NIST for post-quantum cryptography standardization. Understanding its quantum hardness is crucial for assessing the security of these standardized schemes. Inspired by the equivalence between LWE and[…]-
Cryptography
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