ParagonIE_Sodium_Core32_Poly1305_State example

$mlen0 = 64 - ParagonIE_Sodium_Crypto::secretbox_xsalsa20poly1305_ZEROBYTES;
        }
        $block0 .= ParagonIE_Sodium_Core32_Util::substr($plaintext, 0, $mlen0);

        /** @var string $block0 */
        $block0 = ParagonIE_Sodium_Core32_Salsa20::salsa20_xor(
            $block0,
            $realNonce,
            $subkey
        );

        $state = new ParagonIE_Sodium_Core32_Poly1305_State(
            ParagonIE_Sodium_Core32_Util::substr(
                $block0,
                0,
                ParagonIE_Sodium_Crypto::onetimeauth_poly1305_KEYBYTES
            )
        );

        // Pre-write 16 blank bytes for the Poly1305 tag         $start = self::ftell($ofp);
        fwrite($ofp, str_repeat("\x00", 16));

        

    public static function onetimeauth($m, $key)
    {
        if (self::strlen($key) < 32) {
            throw new InvalidArgumentException(
                'Key must be 32 bytes long.'
            );
        }
        $state = new ParagonIE_Sodium_Core32_Poly1305_State(
            self::substr($key, 0, 32)
        );
        return $state
            ->update($m)
            ->finish();
    }

    /** * @internal You should not use this directly from another application * * @param string $mac * @param string $m * @param string $key * @return bool * @throws SodiumException * @throws TypeError */

/** @var string $ciphertext - The encrypted message (sans MAC) */
        $ciphertext = ParagonIE_Sodium_Core32_Util::substr($message, 0, $clen);

        /** @var string The first block of the chacha20 keystream, used as a poly1305 key */
        $block0 = ParagonIE_Sodium_Core32_ChaCha20::stream(
            32,
            $nonce,
            $key
        );

        /* Recalculate the Poly1305 authentication tag (MAC): */
        $state = new ParagonIE_Sodium_Core32_Poly1305_State($block0);
        try {
            ParagonIE_Sodium_Compat::memzero($block0);
        } catch (SodiumException $ex) {
            $block0 = null;
        }
        $state->update($ad);
        $state->update(ParagonIE_Sodium_Core32_Util::store64_le($adlen));
        $state->update($ciphertext);
        $state->update(ParagonIE_Sodium_Core32_Util::store64_le($clen));
        $computed_mac = $state->finish();