Implicit Initialization Vector (IV) for Counter-Based Ciphers in Encapsulating Security Payload (ESP)
RFC 8750

Received changes through RFC Editor sync (created alias RFC 8750, changed title to 'Implicit Initialization Vector (IV) for Counter-Based Ciphers in Encapsulating Security Payload (ESP)', changed abstract to 'Encapsulating Security Payload (ESP) sends an initialization vector (IV) in each packet.  The size of the IV depends on the applied transform and is usually 8 or 16 octets for the transforms defined at the time this document was written.  When used with IPsec, some algorithms, such as AES-GCM, AES-CCM, and ChaCha20-Poly1305, take the IV to generate a nonce that is used as an input parameter for encrypting and decrypting.  This IV must be unique but can be predictable.  As a result, the value provided in the ESP Sequence Number (SN) can be used instead to generate the nonce.  This avoids sending the IV itself and saves 8 octets per packet in the case of AES-GCM, AES-CCM, and ChaCha20-Poly1305.  This document describes how to do this.', changed standardization level to Proposed Standard, changed state to RFC, added RFC published event at 2020-03-11, changed IESG state to RFC Published)