fn aes256gcm_decrypt(
key: &[u8],
iv: &[u8],
ciphertext: &[u8],
tag: &[u8],
aad: &[u8],
) -> Option<Vec<u8>>Expand description
AES-256-GCM decryption for the dir+A256GCM JWE scheme. aad is the
ASCII bytes of the base64url-encoded protected header (RFC 7516 §5.1).