Hybrid Public Key Encryption (HPKE) is a cryptographicprimitive being standardized by the Crypto Forum Research Group (CFRG)within the Internet Research Task Force (IRTF). HPKE schemes combineasymmetric and symmetric cryptographic primitives for efficient authenti-cated encryption of arbitrary-sized plaintexts under a given recipient publickey. This document presents a mechanized cryptographic analysis done withCryptoVerif, of all four HPKE modes, instantiated with a prime-order-groupDiffie-Hellman Key Encapsulation Mechanism (KEM).