   #PHP Manual Function Reference mcal_week_of_year mcrypt_cbc

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LIV. Mcrypt Encryption Functions

Introduction

   This is an interface to the mcrypt library, which supports a wide
   variety of block algorithms such as DES, TripleDES, Blowfish
   (default), 3-WAY, SAFER-SK64, SAFER-SK128, TWOFISH, TEA, RC2 and GOST
   in CBC, OFB, CFB and ECB cipher modes. Additionally, it supports RC6
   and IDEA which are considered "non-free".

Requirements

   These functions work using mcrypt. To use it, download
   libmcrypt-x.x.tar.gz from here and follow the included installation
   instructions. Windows users will find all the needed compiled mcrypt
   binaries here.

   If you linked against libmcrypt 2.4.x or higher, the following
   additional block algorithms are supported: CAST, LOKI97, RIJNDAEL,
   SAFERPLUS, SERPENT and the following stream ciphers: ENIGMA (crypt),
   PANAMA, RC4 and WAKE. With libmcrypt 2.4.x or higher another cipher
   mode is also available; nOFB.

Installation

   You need to compile PHP with the --with-mcrypt[=DIR] parameter to
   enable this extension. DIR is the mcrypt install directory. Make sure
   you compile libmcrypt with the option --disable-posix-threads.

Runtime Configuration

   The behaviour of these functions is affected by settings in php.ini.

   Table 1. Mcrypt configuration options
   Name                  Default Changeable
   mcrypt.algorithms_dir NULL    PHP_INI_ALL
   mcrypt.modes_dir      NULL    PHP_INI_ALL
   For further details and definition of the PHP_INI_* constants see
   ini_set().

Resource Types

   This extension has no resource types defined.

Predefined Constants

   The constants below are defined by this extension, and will only be
   available when the extension has either been compiled into PHP or
   dynamically loaded at runtime.

   Mcrypt can operate in four block cipher modes (CBC, OFB, CFB, and
   ECB). If linked against libmcrypt-2.4.x or higher the functions can
   also operate in the block cipher mode nOFB and in STREAM mode. Below
   you find a list with all supported encryption modes together with the
   constants that are defines for the encryption mode. For a more
   complete reference and discussion see Applied Cryptography by Schneier
   (ISBN 0-471-11709-9).

     * MCRYPT_MODE_ECB (electronic codebook) is suitable for random data,
       such as encrypting other keys. Since data there is short and
       random, the disadvantages of ECB have a favorable negative effect.
     * MCRYPT_MODE_CBC (cipher block chaining) is especially suitable for
       encrypting files where the security is increased over ECB
       significantly.
     * MCRYPT_MODE_CFB (cipher feedback) is the best mode for encrypting
       byte streams where single bytes must be encrypted.
     * MCRYPT_MODE_OFB (output feedback, in 8bit) is comparable to CFB,
       but can be used in applications where error propagation cannot be
       tolerated. It's insecure (because it operates in 8bit mode) so it
       is not recommended to use it.
     * MCRYPT_MODE_NOFB (output feedback, in nbit) is comparable to OFB,
       but more secure because it operates on the block size of the
       algorithm.
     * MCRYPT_MODE_STREAM is an extra mode to include some stream
       algorithms like WAKE or RC4.

   Some other mode and random device constants:

   MCRYPT_ENCRYPT (integer)

   MCRYPT_DECRYPT (integer)

   MCRYPT_DEV_RANDOM (integer)

   MCRYPT_DEV_URANDOM (integer)

   MCRYPT_RAND (integer)

Mcrypt ciphers

   Here is a list of ciphers which are currently supported by the mcrypt
   extension. For a complete list of supported ciphers, see the defines
   at the end of mcrypt.h. The general rule with the mcrypt-2.2.x API is
   that you can access the cipher from PHP with MCRYPT_ciphername. With
   the libmcrypt-2.4.x and libmcrypt-2.5.x API these constants also work,
   but it is possible to specify the name of the cipher as a string with
   a call to mcrypt_module_open().

     * MCRYPT_3DES
     * MCRYPT_ARCFOUR_IV (libmcrypt > 2.4.x only)
     * MCRYPT_ARCFOUR (libmcrypt > 2.4.x only)
     * MCRYPT_BLOWFISH
     * MCRYPT_CAST_128
     * MCRYPT_CAST_256
     * MCRYPT_CRYPT
     * MCRYPT_DES
     * MCRYPT_DES_COMPAT (libmcrypt 2.2.x only)
     * MCRYPT_ENIGMA (libmcrypt > 2.4.x only, alias for MCRYPT_CRYPT)
     * MCRYPT_GOST
     * MCRYPT_IDEA (non-free)
     * MCRYPT_LOKI97 (libmcrypt > 2.4.x only)
     * MCRYPT_MARS (libmcrypt > 2.4.x only, non-free)
     * MCRYPT_PANAMA (libmcrypt > 2.4.x only)
     * MCRYPT_RIJNDAEL_128 (libmcrypt > 2.4.x only)
     * MCRYPT_RIJNDAEL_192 (libmcrypt > 2.4.x only)
     * MCRYPT_RIJNDAEL_256 (libmcrypt > 2.4.x only)
     * MCRYPT_RC2
     * MCRYPT_RC4 (libmcrypt 2.2.x only)
     * MCRYPT_RC6 (libmcrypt > 2.4.x only)
     * MCRYPT_RC6_128 (libmcrypt 2.2.x only)
     * MCRYPT_RC6_192 (libmcrypt 2.2.x only)
     * MCRYPT_RC6_256 (libmcrypt 2.2.x only)
     * MCRYPT_SAFER64
     * MCRYPT_SAFER128
     * MCRYPT_SAFERPLUS (libmcrypt > 2.4.x only)
     * MCRYPT_SERPENT(libmcrypt > 2.4.x only)
     * MCRYPT_SERPENT_128 (libmcrypt 2.2.x only)
     * MCRYPT_SERPENT_192 (libmcrypt 2.2.x only)
     * MCRYPT_SERPENT_256 (libmcrypt 2.2.x only)
     * MCRYPT_SKIPJACK (libmcrypt > 2.4.x only)
     * MCRYPT_TEAN (libmcrypt 2.2.x only)
     * MCRYPT_THREEWAY
     * MCRYPT_TRIPLEDES (libmcrypt > 2.4.x only)
     * MCRYPT_TWOFISH (for older mcrypt 2.x versions, or mcrypt > 2.4.x )
     * MCRYPT_TWOFISH128 (TWOFISHxxx are available in newer 2.x versions,
       but not in the 2.4.x versions)
     * MCRYPT_TWOFISH192
     * MCRYPT_TWOFISH256
     * MCRYPT_WAKE (libmcrypt > 2.4.x only)
     * MCRYPT_XTEA (libmcrypt > 2.4.x only)

   You must (in CFB and OFB mode) or can (in CBC mode) supply an
   initialization vector (IV) to the respective cipher function. The IV
   must be unique and must be the same when decrypting/encrypting. With
   data which is stored encrypted, you can take the output of a function
   of the index under which the data is stored (e.g. the MD5 key of the
   filename). Alternatively, you can transmit the IV together with the
   encrypted data (see chapter 9.3 of Applied Cryptography by Schneier
   (ISBN 0-471-11709-9) for a discussion of this topic).

Examples

   Mcrypt can be used to encrypt and decrypt using the above mentioned
   ciphers. If you linked against libmcrypt-2.2.x, the four important
   mcrypt commands (mcrypt_cfb(), mcrypt_cbc(), mcrypt_ecb(), and
   mcrypt_ofb()) can operate in both modes which are named MCRYPT_ENCRYPT
   and MCRYPT_DECRYPT, respectively.

   Example 1. Encrypt an input value with TripleDES under 2.2.x in ECB
   mode
   <?php
   $key = "this is a secret key";
   $input = "Let us meet at 9 o'clock at the secret place.";
   $encrypted_data = mcrypt_ecb (MCRYPT_3DES, $key, $input,
   MCRYPT_ENCRYPT);
   ?>
   This example will give you the encrypted data as a string in
   $encrypted_data.

   If you linked against libmcrypt 2.4.x or 2.5.x, these functions are
   still available, but it is recommended that you use the advanced
   functions.

   Example 2. Encrypt an input value with TripleDES under 2.4.x and
   higher in ECB mode
   <?php
       $key = "this is a secret key";
       $input = "Let us meet at 9 o'clock at the secret place.";
       $td = mcrypt_module_open('tripledes', '', 'ecb', '');
       $iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
       mcrypt_generic_init($td, $key, $iv);
       $encrypted_data = mcrypt_generic($td, $input);
       mcrypt_generic_deinit($td);
       mcrypt_module_close($td);
   ?>
   This example will give you the encrypted data as a string in
   $encrypted_data. For a full example see mcrypt_module_open().

   Table of Contents
   mcrypt_cbc -- Encrypt/decrypt data in CBC mode
   mcrypt_cfb -- Encrypt/decrypt data in CFB mode
   mcrypt_create_iv --  Create an initialization vector (IV) from a
          random source

   mcrypt_decrypt -- Decrypts crypttext with given parameters
   mcrypt_ecb -- Encrypt/decrypt data in ECB mode
   mcrypt_enc_get_algorithms_name -- Returns the name of the opened
          algorithm

   mcrypt_enc_get_block_size -- Returns the blocksize of the opened
          algorithm

   mcrypt_enc_get_iv_size -- Returns the size of the IV of the opened
          algorithm

   mcrypt_enc_get_key_size -- Returns the maximum supported keysize of
          the opened mode

   mcrypt_enc_get_modes_name -- Returns the name of the opened mode
   mcrypt_enc_get_supported_key_sizes -- Returns an array with the
          supported keysizes of the opened algorithm

   mcrypt_enc_is_block_algorithm_mode -- Checks whether the encryption of
          the opened mode works on blocks

   mcrypt_enc_is_block_algorithm -- Checks whether the algorithm of the
          opened mode is a block algorithm

   mcrypt_enc_is_block_mode -- Checks whether the opened mode outputs
          blocks

   mcrypt_enc_self_test -- This function runs a self test on the opened
          module

   mcrypt_encrypt -- Encrypts plaintext with given parameters
   mcrypt_generic_deinit --  This function deinitializes an encryption
          module

   mcrypt_generic_end -- This function terminates encryption
   mcrypt_generic_init -- This function initializes all buffers needed
          for encryption

   mcrypt_generic -- This function encrypts data
   mcrypt_get_block_size -- Get the block size of the specified cipher
   mcrypt_get_cipher_name -- Get the name of the specified cipher
   mcrypt_get_iv_size --  Returns the size of the IV belonging to a
          specific cipher/mode combination

   mcrypt_get_key_size -- Get the key size of the specified cipher
   mcrypt_list_algorithms -- Get an array of all supported ciphers
   mcrypt_list_modes -- Get an array of all supported modes
   mcrypt_module_close --  Close the mcrypt module
   mcrypt_module_get_algo_block_size -- Returns the blocksize of the
          specified algorithm

   mcrypt_module_get_algo_key_size -- Returns the maximum supported
          keysize of the opened mode

   mcrypt_module_get_supported_key_sizes -- Returns an array with the
          supported keysizes of the opened algorithm

   mcrypt_module_is_block_algorithm_mode -- This function returns if the
          the specified module is a block algorithm or not

   mcrypt_module_is_block_algorithm -- This function checks whether the
          specified algorithm is a block algorithm

   mcrypt_module_is_block_mode -- This function returns if the the
          specified mode outputs blocks or not

   mcrypt_module_open -- Opens the module of the algorithm and the mode
          to be used

   mcrypt_module_self_test -- This function runs a self test on the
          specified module

   mcrypt_ofb -- Encrypt/decrypt data in OFB mode
   mdecrypt_generic -- Decrypt data
   ______________________________________________________________________

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