SPRUJF2A March 2026 – March 2026 AM13E23019
For GHASH operations, the engine performs a modular polynomial multiplication in the GF(2128) field. The result is XOR-ed with the encrypted GCM initialization vector (referred to as ‘Y0-encrypted’). Y0-encrypted is only relevant when the engine is performing a complete GCM operation, therefore in other modes the value of Y0-encrypted is forced to zero.
Also, for GCM mode only, the GCM ‘Hash key’ or ‘H’ input can be pre-calculated and supplied to the engine directly, or it can be calculated by the engine internally, by encrypting the value ‘0’, using the encryption key.