<?php

/**
 * Joomla! Content Management System
 *
 * @copyright  (C) 2016 Open Source Matters, Inc. <https://www.joomla.org>
 * @license    GNU General Public License version 2 or later; see LICENSE.txt
 */

namespace Joomla\CMS\Encrypt\AES;

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

/**
 * Interface for AES encryption adapters
 *
 * @since    4.0.0
 */
interface AesInterface
{
    /**
     * Sets the AES encryption mode.
     *
     * WARNING: The strength is deprecated as it has a different effect in MCrypt and OpenSSL. MCrypt was abandoned in
     * 2003 before the Rijndael-128 algorithm was officially the Advanced Encryption Standard (AES). MCrypt also offered
     * Rijndael-192 and Rijndael-256 algorithms with different block sizes. These are NOT used in AES. OpenSSL, however,
     * implements AES correctly. It always uses a 128-bit (16 byte) block. The 192 and 256 bit strengths refer to the
     * key size, not the block size. Therefore using different strengths in MCrypt and OpenSSL will result in different
     * and incompatible ciphertexts.
     *
     * TL;DR: Always use $strength = 128!
     *
     * @param   string  $mode      Choose between CBC (recommended) or ECB
     * @param   int     $strength  Bit strength of the key (128, 192 or 256 bits). DEPRECATED. READ NOTES ABOVE.
     *
     * @return  mixed
     */
    public function setEncryptionMode($mode = 'cbc', $strength = 128);

    /**
     * Encrypts a string. Returns the raw binary ciphertext.
     *
     * WARNING: The plaintext is zero-padded to the algorithm's block size. You are advised to store the size of the
     * plaintext and trim the string to that length upon decryption.
     *
     * @param   string       $plainText  The plaintext to encrypt
     * @param   string       $key        The raw binary key (will be zero-padded or chopped if its size is different than the block size)
     * @param   null|string  $iv         The initialization vector (for CBC mode algorithms)
     *
     * @return  string  The raw encrypted binary string.
     */
    public function encrypt($plainText, $key, $iv = null);

    /**
     * Decrypts a string. Returns the raw binary plaintext.
     *
     * $ciphertext MUST start with the IV followed by the ciphertext, even for EBC data (the first block of data is
     * dropped in EBC mode since there is no concept of IV in EBC).
     *
     * WARNING: The returned plaintext is zero-padded to the algorithm's block size during encryption. You are advised
     * to trim the string to the original plaintext's length upon decryption. While rtrim($decrypted, "\0") sounds
     * appealing it's NOT the correct approach for binary data (zero bytes may actually be part of your plaintext, not
     * just padding!).
     *
     * @param   string  $cipherText  The ciphertext to encrypt
     * @param   string  $key         The raw binary key (will be zero-padded or chopped if its size is different than the block size)
     *
     * @return  string  The raw unencrypted binary string.
     */
    public function decrypt($cipherText, $key);

    /**
     * Returns the encryption block size in bytes
     *
     * @return  integer
     */
    public function getBlockSize();

    /**
     * Is this adapter supported?
     *
     * @return  boolean
     */
    public function isSupported();
}
