Verifying Cryptographic Code in C: Some Experience and the Csec Challenge

The security of much critical infrastructure depends in part on cryptographic software coded in C, and yet vulnerabilities continue to be discovered in such software. We describe recent progress on checking the security of C code implementing cryptographic software. In particular, we describe projects that combine verification-condition generation and symbolic execution techniques for C, with methods for stating and verifying security properties of abstract models of cryptographic protocols. We illustrate these techniques on C code for a simple two-message protocol

A Framework for Game-Based Security Proofs ⋆

Abstract. To be accepted, a cryptographic scheme must come with a proof that it satisfies some standard security properties. However, because cryptographic schemes are based on non-trivial mathematics, proofs are error-prone and difficult to check. The main contributions of this paper are a refinement of the game-based approach to security proofs, and its implementation on top of the proof assistant Coq. The proof assistant checks that the proof is correct and deals with the mundane part of the proof. An interesting feature of our framework is that our proofs are formal enough to be mechanically checked, but still readable enough to be humanly checked. We illustrate the use of our framework by proving in a systematic way the so-called semantic security of the encryption scheme Elgamal and its hashed version

Model Checking Security Protocols

The formal analysis of security protocols is a prime example of a domain where model checking has been successfully applied. Although security protocols are typically small, analysis by hand is difficult as a protocol should work even when arbitrarily many runs are interleaved and in the presence of an adversary. Specialized model-checking techniques have been developed that address both the problems of unbounded, interleaved runs and a prolific, highly nondeterministic adversary.These techniques have been implemented in model-checking tools that now scale to protocols of realistic size and can be used to aid protocol design and standardization.In this chapter, we provide an overview of the main applications of model checking in security protocol analysis. We explain the central concepts involved in the analysis of security protocols: the abstraction of messages, protocols as role automata, the adversary model, and property specification. We explain and relate the main algorithms used and describe systems based on them. We also give examples of the successful applications of model checking to protocol standards. Finally, we provide an outlook on the field: What is possible with the state of the art and what are the future challenges