streamXorIc example

$state->update(ParagonIE_Sodium_Core32_Util::store64_le($adlen));
        $state->update($ciphertext);
        $state->update(ParagonIE_Sodium_Core32_Util::store64_le($clen));
        $computed_mac = $state->finish();

        /* 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::streamXorIc(
            $ciphertext,
            $nonce,
            $key,
            ParagonIE_Sodium_Core32_Util::store64_le(1)
        );
    }

    /** * AEAD Encryption with ChaCha20-Poly1305 * * @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 */

$state->update(ParagonIE_Sodium_Core_Util::store64_le($adlen));
        $state->update($ciphertext);
        $state->update(ParagonIE_Sodium_Core_Util::store64_le($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::streamXorIc(
            $ciphertext,
            $nonce,
            $key,
            ParagonIE_Sodium_Core_Util::store64_le(1)
        );
    }

    /** * AEAD Encryption with ChaCha20-Poly1305 * * @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 */

if (ParagonIE_Sodium_Core_Util::strlen($nonce) !== self::CRYPTO_STREAM_XCHACHA20_NONCEBYTES) {
            throw new SodiumException('Argument 2 must be CRYPTO_SECRETBOX_XCHACHA20_NONCEBYTES long.');
        }
        if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_STREAM_XCHACHA20_KEYBYTES) {
            throw new SodiumException('Argument 3 must be CRYPTO_SECRETBOX_XCHACHA20_KEYBYTES long.');
        }

        if (self::useNewSodiumAPI() && !$dontFallback) {
            return sodium_crypto_stream_xchacha20_xor($message, $nonce, $key);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Core32_XChaCha20::streamXorIc($message, $nonce, $key);
        }
        return ParagonIE_Sodium_Core_XChaCha20::streamXorIc($message, $nonce, $key);
    }

    /** * DANGER! UNAUTHENTICATED ENCRYPTION! * * Unless you are following expert advice, do not use this feature. * * Algorithm: XChaCha20 * * This DOES NOT provide ciphertext integrity. * * @param string $message Plaintext message * @param string $nonce Number to be used Once; must be 24 bytes * @param int $counter * @param string $key Encryption key * @return string Encrypted text which is vulnerable to chosen- * ciphertext attacks unless you implement some * other mitigation to the ciphertext (i.e. * Encrypt then MAC) * @param bool $dontFallback * @throws SodiumException * @throws TypeError * @psalm-suppress MixedArgument */