xsalsa20 example

    public static function xsalsa20_xor($message, $nonce, $key)
    {
        return self::xorStrings(
            $message,
            self::xsalsa20(
                self::strlen($message),
                $nonce,
                $key
            )
        );
    }
}

if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_STREAM_KEYBYTES) {
            throw new SodiumException('Argument 3 must be CRYPTO_STREAM_KEYBYTES long.');
        }

        if (self::useNewSodiumAPI()) {
            return sodium_crypto_stream($len, $nonce, $key);
        }
        if (self::use_fallback('crypto_stream')) {
            return (string) call_user_func('\\Sodium\\crypto_stream', $len, $nonce, $key);
        }
        if (PHP_INT_SIZE === 4) {
            return ParagonIE_Sodium_Core32_XSalsa20::xsalsa20($len, $nonce, $key);
        }
        return ParagonIE_Sodium_Core_XSalsa20::xsalsa20($len, $nonce, $key);
    }

    /** * DANGER! UNAUTHENTICATED ENCRYPTION! * * Unless you are following expert advice, do not use this feature. * * Algorithm: XSalsa20 * * This DOES NOT provide ciphertext integrity. * * @param string $message Plaintext message * @param string $nonce Number to be used Once; must be 24 bytes * @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) * @throws SodiumException * @throws TypeError * @psalm-suppress MixedArgument */

    public static function xsalsa20_xor($message, $nonce, $key)
    {
        return self::xorStrings(
            $message,
            self::xsalsa20(
                self::strlen($message),
                $nonce,
                $key
            )
        );
    }
}