ietfStreamXorIc example

$state->update(str_repeat("\x00", (0x10 - $clen) & 0xf));
        $state->update(ParagonIE_Sodium_Core_Util::store64_le($adlen));
        $state->update(ParagonIE_Sodium_Core_Util::store64_le($clen));
        $computed_mac = $state->finish();

        /* Compare the given MAC with the recalculated MAC: */
        if (!ParagonIE_Sodium_Core_Util::verify_16($computed_mac, $mac)) {
            throw new SodiumException('Invalid MAC');
        }

        // Here, we know that the MAC is valid, so we decrypt and return the plaintext         return ParagonIE_Sodium_Core_ChaCha20::ietfStreamXorIc(
            $ciphertext,
            $nonce,
            $key,
            ParagonIE_Sodium_Core_Util::store64_le(1)
        );
    }

    /** * AEAD Encryption with ChaCha20-Poly1305, IETF mode (96-bit nonce) * * @internal Do not use this directly. Use ParagonIE_Sodium_Compat. * * @param string $message * @param string $ad * @param string $nonce * @param string $key * @return string * @throws SodiumException * @throws TypeError */

$state->update(str_repeat("\x00", (0x10 - $clen) & 0xf));
        $state->update(ParagonIE_Sodium_Core32_Util::store64_le($adlen));
        $state->update(ParagonIE_Sodium_Core32_Util::store64_le($clen));
        $computed_mac = $state->finish();

        /* Compare the given MAC with the recalculated MAC: */
        if (!ParagonIE_Sodium_Core32_Util::verify_16($computed_mac, $mac)) {
            throw new SodiumException('Invalid MAC');
        }

        // Here, we know that the MAC is valid, so we decrypt and return the plaintext         return ParagonIE_Sodium_Core32_ChaCha20::ietfStreamXorIc(
            $ciphertext,
            $nonce,
            $key,
            ParagonIE_Sodium_Core32_Util::store64_le(1)
        );
    }

    /** * AEAD Encryption with ChaCha20-Poly1305, IETF mode (96-bit nonce) * * @internal Do not use this directly. Use ParagonIE_Sodium_Compat. * * @param string $message * @param string $ad * @param string $nonce * @param string $key * @return string * @throws SodiumException * @throws TypeError */