Do you think you know ElGamal encryption? Think twice.
We uncover vulnerabilities in the OpenPGP ecosystem stemming from confusion about the definition of ElGamal encryption (and the lack of an unequivocable standard). The first vulnerability leads to practical plaintext recovery in a limited number of cases. The second one, combined with side-channel leakage we found in some popular OpenPGP libraries, leads to feasible key recovery, in relatively rare cases.
Joint work with B. Poettering and A. Sorniotti