We verify cryptographic protocols coded in C for correspondence properties with respect to the computational model of cryptography. Our first step uses symbolic execution to extract a process calculus model from a C implementation of the protocol. The new contribution is the second step in which we translate the extracted model to a CryptoVerif protocol description, such that successful verification with CryptoVerif implies the security of the original C implementation. We implement our method

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... nd apply it to verify several protocols out of reach of previous work in the symbolic model (using ProVerif), either due to the use of XOR and Diffie-Hellman commitments, or due to the lack of an appropriate computational soundness result. We analyse only a single execution path, so our tool is limited to code following a fixed protocol narration. This is the first security analysis of C code to target a verifier for the computational model. We successfully verify over 3000 LOC. One example (about 1000 LOC) is independently written and currently in testing phase for industrial deployment; during its analysis we uncovered a vulnerability now fixed by its author.