public static void verifyMac(final byte[] key, byte[] data, byte[] mac)
      throws GeneralSecurityException {
    if (!Bytes.equal(computeMac(key, data), mac)) {
      throw new GeneralSecurityException("invalid MAC");
    }
  }
Verifies Poly1305 {@ mac} over {@code data} using {@code key}.
java_src/src/main/java/com/google/crypto/tink/aead/internal/Poly1305.java