Function hpke::ComputeNonce

pub fn ComputeNonce(aead_id: AEAD, base_nonce: &Nonce, seq: u32) -> ByteSeq

Compute Nonce

The sequence number provides nonce uniqueness: The nonce used for each encryption or decryption operation is the result of XORing base_nonce with the current sequence number, encoded as a big-endian integer of the same length as base_nonce. Implementations MAY use a sequence number that is shorter than the nonce length (padding on the left with zero), but MUST raise an error if the sequence number overflows.

def Context<ROLE>.ComputeNonce(seq):
  seq_bytes = I2OSP(seq, Nn)
  return xor(self.base_nonce, seq_bytes)