<?php

/**
 * Joomla! Content Management System
 *
 * @copyright  (C) 2013 Open Source Matters, Inc. <https://www.joomla.org>
 * @license    GNU General Public License version 2 or later; see LICENSE.txt
 * @note    This file has been modified by the Joomla! Project and no longer reflects the original work of its author.
 */

namespace Joomla\CMS\Encrypt;

use Joomla\CMS\Encrypt\AES\AesInterface;
use Joomla\CMS\Encrypt\AES\Mcrypt;
use Joomla\CMS\Encrypt\AES\OpenSSL;

// phpcs:disable PSR1.Files.SideEffects
\defined('_JEXEC') or die;
// phpcs:enable PSR1.Files.SideEffects

/**
 * A simple implementation of AES-128, AES-192 and AES-256 encryption using the
 * high performance mcrypt library.
 *
 * @since    1.0
 */
class Aes
{
    /**
     * The cipher key.
     *
     * @var   string
     */
    protected $key = '';

    /**
     * The AES encryption adapter in use.
     *
     * @var  AesInterface
     */
    protected $adapter;

    /**
     * Initialise the AES encryption object.
     *
     * Note: If the key is not 16 bytes this class will do a stupid key expansion for legacy reasons (produce the
     * SHA-256 of the key string and throw away half of it).
     *
     * @param   string          $key      The encryption key (password). It can be a raw key (16 bytes) or a passphrase.
     * @param   int             $strength Bit strength (128, 192 or 256) – ALWAYS USE 128 BITS. THIS PARAMETER IS DEPRECATED.
     * @param   string          $mode     Encryption mode. Can be ebc or cbc. We recommend using cbc.
     * @param   string          $priority Priority which adapter we should try first
     *
     * @deprecated  4.3 $strength will be removed in 6.0
     */
    public function __construct($key, $strength = 128, $mode = 'cbc', $priority = 'openssl')
    {
        if ($priority === 'openssl') {
            $this->adapter = new OpenSSL();

            if (!$this->adapter->isSupported()) {
                $this->adapter = new Mcrypt();
            }
        } else {
            $this->adapter = new Mcrypt();

            if (!$this->adapter->isSupported()) {
                $this->adapter = new OpenSSL();
            }
        }

        $this->adapter->setEncryptionMode($mode, $strength);
        $this->setPassword($key, true);
    }

    /**
     * Sets the password for this instance.
     *
     * WARNING: Do not use the legacy mode, it's insecure
     *
     * @param   string $password   The password (either user-provided password or binary encryption key) to use
     * @param   bool   $legacyMode True to use the legacy key expansion. We recommend against using it.
     *
     * @since    4.0.0
     * @return   void
     */
    public function setPassword($password, $legacyMode = false)
    {
        $this->key = $password;

        $passLength = \strlen($password);

        if (\function_exists('mb_strlen')) {
            $passLength = mb_strlen($password, 'ASCII');
        }

        // Legacy mode was doing something stupid, requiring a key of 32 bytes. DO NOT USE LEGACY MODE!
        if ($legacyMode && ($passLength != 32)) {
            // Legacy mode: use the sha256 of the password
            $this->key = hash('sha256', $password, true);

            // We have to trim or zero pad the password (we end up throwing half of it away in Rijndael-128 / AES...)
            $this->key = $this->adapter->resizeKey($this->key, $this->adapter->getBlockSize());
        }
    }

    /**
     * Encrypts a string using AES
     *
     * @param   string $stringToEncrypt The plaintext to encrypt
     * @param   bool   $base64encoded   Should I Base64-encode the result?
     *
     * @return   string  The cryptotext. Please note that the first 16 bytes of
     *                   the raw string is the IV (initialisation vector) which
     *                   is necessary for decoding the string.
     */
    public function encryptString($stringToEncrypt, $base64encoded = true)
    {
        $blockSize = $this->adapter->getBlockSize();
        $randVal   = new Randval();
        $iv        = $randVal->generate($blockSize);

        $key        = $this->getExpandedKey($blockSize, $iv);
        $cipherText = $this->adapter->encrypt($stringToEncrypt, $key, $iv);

        // Optionally pass the result through Base64 encoding
        if ($base64encoded) {
            $cipherText = base64_encode($cipherText);
        }

        // Return the result
        return $cipherText;
    }

    /**
     * Decrypts a ciphertext into a plaintext string using AES
     *
     * @param   string $stringToDecrypt The ciphertext to decrypt. The first 16 bytes of the raw string must contain
     *                                  the IV (initialisation vector).
     * @param   bool   $base64encoded   Should I Base64-decode the data before decryption?
     *
     * @return   string  The plain text string
     */
    public function decryptString($stringToDecrypt, $base64encoded = true)
    {
        if ($base64encoded) {
            $stringToDecrypt = base64_decode($stringToDecrypt);
        }

        // Extract IV
        $iv_size = $this->adapter->getBlockSize();
        $iv      = substr($stringToDecrypt, 0, $iv_size);
        $key     = $this->getExpandedKey($iv_size, $iv);

        // Decrypt the data
        $plainText = $this->adapter->decrypt($stringToDecrypt, $key);

        return $plainText;
    }

    /**
     * Is AES encryption supported by this PHP installation?
     *
     * @return boolean
     */
    public static function isSupported()
    {
        $adapter = new OpenSSL();

        if (!$adapter->isSupported()) {
            $adapter = new Mcrypt();

            if (!$adapter->isSupported()) {
                return false;
            }
        }

        if (!\function_exists('base64_encode')) {
            return false;
        }

        if (!\function_exists('base64_decode')) {
            return false;
        }

        if (!\function_exists('hash_algos')) {
            return false;
        }

        $algorithms = hash_algos();

        if (!\in_array('sha256', $algorithms)) {
            return false;
        }

        return true;
    }

    /**
     * Get the expanded key
     *
     * @param   integer  $blockSize  Blocksize to process
     * @param   string   $iv         IV
     *
     * @return   string
     */
    public function getExpandedKey($blockSize, $iv)
    {
        $key        = $this->key;
        $passLength = \strlen($key);

        if (\function_exists('mb_strlen')) {
            $passLength = mb_strlen($key, 'ASCII');
        }

        if ($passLength != $blockSize) {
            $iterations = 1000;
            $salt       = $this->adapter->resizeKey($iv, 16);
            $key        = hash_pbkdf2('sha256', $this->key, $salt, $iterations, $blockSize, true);
        }

        return $key;
    }
}

if (!\function_exists('hash_pbkdf2')) {
    /**
     * Shim for missing hash_pbkdf2
     *
     * @param   string   $algo       Algorithm to use
     * @param   string   $password   Plaintext password
     * @param   string   $salt       Salt for the hash
     * @param   integer  $count      Number of iterations
     * @param   integer  $length     Length
     * @param   boolean  $rawOutput  Raw output
     *
     * @return   string  Hashed string
     */
    function hash_pbkdf2($algo, $password, $salt, $count, $length = 0, $rawOutput = false)
    {
        if (!\in_array(strtolower($algo), hash_algos())) {
            trigger_error(__FUNCTION__ . '(): Unknown hashing algorithm: ' . $algo, E_USER_WARNING);
        }

        if (!is_numeric($count)) {
            trigger_error(__FUNCTION__ . '(): expects parameter 4 to be long, ' . \gettype($count) . ' given', E_USER_WARNING);
        }

        if (!is_numeric($length)) {
            trigger_error(__FUNCTION__ . '(): expects parameter 5 to be long, ' . \gettype($length) . ' given', E_USER_WARNING);
        }

        if ($count <= 0) {
            trigger_error(__FUNCTION__ . '(): Iterations must be a positive integer: ' . $count, E_USER_WARNING);
        }

        if ($length < 0) {
            trigger_error(__FUNCTION__ . '(): Length must be greater than or equal to 0: ' . $length, E_USER_WARNING);
        }

        $output      = '';
        $block_count = $length ? ceil($length / \strlen(hash($algo, '', $rawOutput))) : 1;

        for ($i = 1; $i <= $block_count; $i++) {
            $last = $xorsum = hash_hmac($algo, $salt . pack('N', $i), $password, true);

            for ($j = 1; $j < $count; $j++) {
                $xorsum ^= ($last = hash_hmac($algo, $last, $password, true));
            }

            $output .= $xorsum;
        }

        if (!$rawOutput) {
            $output = bin2hex($output);
        }

        return $length ? substr($output, 0, $length) : $output;
    }
}
