Random-Access Authenticated Encryption

This document defines Random-Access Authenticated Encryption (raAE), a mechanism for encrypting segmented content that supports decryption of individual segments without processing others, selective re- encryption of individual segments in place, and content-level integrity via an accumulator binding all segment authentication tags. raAE is parameterized over an Authenticated Encryption with Associated Data (AEAD) algorithm, a key derivation function (KDF), segment size, epoch length, and nonce generation mode. raAE does not define wire formats, IANA registries, or key management; applications instantiate it with a chosen parameter set and protocol identifier. This document also defines "raAE-v1", a concrete profile with test vectors, supporting five AEAD algorithms: AES-256-GCM, ChaCha20-Poly1305, AES-256-GCM-SIV, AEGIS-256, and AEGIS-256X2, each with HKDF-SHA-256 and 65536-octet segments.