<?php
/**
 * @package   AkeebaBackup
 * @copyright Copyright (c)2006-2018 Nicholas K. Dionysopoulos / Akeeba Ltd
 * @license   GNU General Public License version 3, or later
 *
 * @since     3.0
 */

namespace Akeeba\Engine\Util\AesAdapter;

// Protection against direct access
defined('AKEEBAENGINE') or die();

/**
 * Interface for AES encryption adapters
 */
interface AdapterInterface
{
	/**
	 * 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  int
	 */
	public function getBlockSize();

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