Attacking end-to-end email encryption

In this talk, I’ll present several attacks that leak the plaintext of OpenPGP or S/MIME encrypted emails to an attacker. Some of the attacks are technically interesting, i.e. the two different efail attacks, some are somewhat silly, yet effective. Some abuse HTML emails, some also work with plain ASCII emails. Furthermore, I’ll discuss our lessons learned and describe the efail-related changes to mail clients and the OpenPGP and S/MIME standards.