HPKE

HPKE, or Hybrid Public Key Encryption, is a cryptographic standard designed to provide authenticated encryption for data. It allows one party to encrypt data for another party, ensuring that only the intended recipient can decrypt it and that the sender's identity is verifiable. HPKE combines several cryptographic primitives to achieve this goal. At its core, HPKE uses a public-key encryption scheme to establish a shared secret key. This public-key mechanism can be chosen from various options, such as RSA or Elliptic Curve Integrated Encryption Scheme (ECIES). Once a shared secret is established, it is then used with a symmetric encryption algorithm, like AES, to encrypt the actual data. This hybrid approach leverages the efficiency of symmetric encryption for bulk data while using public-key cryptography for secure key establishment.

In addition to confidentiality, HPKE also provides authenticated encryption. This means that not only is the data kept secret, but its integrity is also protected. Any tampering with the ciphertext will be detected during decryption. Furthermore, HPKE includes mechanisms for sender authentication. This can be achieved through digital signatures or other identity-based cryptographic methods, allowing the recipient to verify that the encrypted data originated from the expected sender. The HPKE standard is designed to be flexible, allowing for different combinations of underlying cryptographic algorithms to be used, catering to various security and performance requirements. It aims to simplify the implementation of secure communication protocols by providing a standardized and robust framework for authenticated encryption.