Module gcm 

Galois/Counter Mode (GCM) for authenticated encryption

GCM is an authenticated encryption with associated data (AEAD) mode that provides both confidentiality and authenticity. It combines the Counter (CTR) mode with the GHASH authentication function.

Implementation Note

This implementation is tested against the repository’s byte-bound CAVP/ACVP-format known-answer data. The local fixtures’ upstream acquisition provenance is unverified; vector tests are not a FIPS validation or certification claim.

Timing behavior

Authentication tag bytes are compared with dcrypt’s owned constant-time trait after checking the public length. Input lengths, state errors, and authentication results use ordinary branching. No blanket side-channel guarantee is made for every backend, compiler, or target.

Structs

Gcm

GCM mode implementation

GcmDecryptOperation

Operation for GCM decryption operations

GcmEncryptOperation

Operation for GCM encryption operations

Traits

GcmKey

Key construction needed by the generic SymmetricCipher adapter.