Mcrypt

Mcrypt is a library for encrypting and decrypting data, which was previously a popular choice in many PHP applications. It provided a range of encryption algorithms and modes, allowing developers to implement data encryption in their projects. However, it's important to note the current status and historical context of Mcrypt in PHP and general cryptographic practices.

Mcrypt supported a variety of encryption algorithms, including DES, TripleDES, Blowfish, Twofish, and RIJNDAEL (which is the basis for AES). It offered several modes of operation for encryption, such as CBC (Cipher Block Chaining), CFB (Cipher Feedback), and OFB (Output Feedback). Mcrypt functions were straightforward to use, offering a procedural interface for encryption and decryption tasks.

Mcrypt was widely used in PHP applications for many years due to its ease of use and the wide range of algorithms it supported. As of PHP 7.1, Mcrypt was deprecated, and it was removed entirely in PHP 7.2. This decision was made due to several factors:

• The library had not been actively maintained for years.
• Newer, more robust, and actively maintained cryptographic libraries like OpenSSL and Sodium (included in PHP 7.2 and later) became available.
• Concerns about the security and modern cryptographic standards of Mcrypt.

Due to its deprecation and removal, Mcrypt should not be used in new PHP projects. Instead, it's recommended to use modern and actively supported libraries like OpenSSL or Sodium. For legacy projects that still use Mcrypt, it's advisable to plan for migration to a more current and supported encryption library.

An example of its use:

$key = 'your-secret-key';
$input = 'Sensitive data';

$td = mcrypt_module_open('rijndael-256', '', 'cbc', '');
$iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
mcrypt_generic_init($td, $key, $iv);

$encrypted_data = mcrypt_generic($td, $input);
mcrypt_generic_deinit($td);
mcrypt_module_close($td);