wcV1VerifyHmac function
Verify the HMAC of a payload (over ciphertext || iv).
Implementation
bool wcV1VerifyHmac(WcV1Payload payload, Uint8List key32) {
final ct = hexDecode(payload.data);
final iv = hexDecode(payload.iv);
final mac = hmacSha256(key32, _concat(ct, iv));
return _constantTimeEquals(hexEncode(mac), payload.hmac);
}