What is mcrypt php extension?

• Introduction
• Installing/Configuring
  • Requirements
  • Installation
  • Runtime Configuration
  • Resource Types
• Predefined Constants
• Mcrypt ciphers
• Mcrypt Functions
  • mcrypt_create_iv — Creates an initialization vector (IV) from a random source
  • mcrypt_decrypt — Decrypts crypttext with given parameters
  • 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 — 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_init — This function initializes all buffers needed for encryption
  • mcrypt_generic — This function encrypts data
  • mcrypt_get_block_size — Gets the block size of the specified cipher
  • mcrypt_get_cipher_name — Gets 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 — Gets the key size of the specified cipher
  • mcrypt_list_algorithms — Gets an array of all supported ciphers
  • mcrypt_list_modes — Gets an array of all supported modes
  • mcrypt_module_close — Closes 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 — Returns if 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 — Returns if 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
  • mdecrypt_generic — Decrypts data

Kyle T ¶

4 years ago

This was posted before by another user but has been downvoted. I just wanted to confirm that we suffered massive performance issues related to mcrypt on CentOS (PHP 5.6.32) that are not present in other flavors of Linux.

A sampling of 25,000 encrypts/decrypts takes 4-5x longer when running mcrypt on Centos 7 as compared to Ubuntu. Switching out mcrypt for OpenSSL on Centos will result in a massive increase in performance.

For lower traffic website it can be negligible, but when you start seeing significant traffic/load it will quickly bring down a server.

Maarten Malaise ¶

12 years ago

people using phpmyadmin are redirected to this manual if they don't have mcrypt installed. If you want to install mcrypt on debian, first check your php version:

yourserver# php --version

Then install the appropriate version of mcrypt (php5-mcrypt if your php version is 5.x)

yourserver# apt-get install php4-mcrypt
...or...
yourserver# apt-get install php5-mcrypt

Anonymous ¶

10 years ago

These are two simple functions I built for 256-bit encryption/decryption with mcrypt.  I've decided to use MCRYPT_RIJNDAEL_128 because it's AES-compliant, and MCRYPT_MODE_CBC.  (ECB mode is inadequate for many purposes because it does not use an IV.)

This function stores a hash of the data to verify that the data was decrypted successfully, but this could be easily removed if necessary.

function encrypt($decrypted, $password, $salt='!kQm*fF3pXe1Kbm%9') {
// Build a 256-bit $key which is a SHA256 hash of $salt and $password.
$key = hash('SHA256', $salt . $password, true);
// Build $iv and $iv_base64.  We use a block size of 128 bits (AES compliant) and CBC mode.  (Note: ECB mode is inadequate as IV is not used.)
srand(); $iv = mcrypt_create_iv(mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC), MCRYPT_RAND);
if (strlen($iv_base64 = rtrim(base64_encode($iv), '=')) != 22) return false;
// Encrypt $decrypted and an MD5 of $decrypted using $key.  MD5 is fine to use here because it's just to verify successful decryption.
$encrypted = base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key, $decrypted . md5($decrypted), MCRYPT_MODE_CBC, $iv));
// We're done!
return $iv_base64 . $encrypted;
}

function

ghoffman at salientdigital dot com ¶

11 years ago

If you want a quick way to see what ciphers, modes, key, block and iv sizes are supported on your server, try something like the following.

Note: I used this simple bash: `locate libmcrypt` from terminal on Mac OS X to determine the install paths to the algorithms and modes directories. Lots of function calls generate warnings for certain ciphers, hence the use of error suppression.

$modes

  
            key_size: ". ($key_size?$key_size:'n/a') 
      ."    block_size: ". ($block_size?$block_size:'n/a') 
      ."    iv_size: ". ($iv_size?$iv_size:'n/a') 
      ."  

Daniel Esteve ¶

5 years ago

The Mcrypt library has been declared DEPRECATED since PHP 7.1, to use in its OpenSSL