PHP encryption extension library Mcrypt installation and application examples_PHP tutorial

If we want to use the PHP Mcrypt encryption extension library in php, we must first install the encryption extension library and then use it, because it is not installed by default like the gd library.

A brief introduction to mcrypt

When PHP programmers write code programs, in addition to ensuring the high performance of the code, there is another very important point, which is the security of the program. In addition to several of its own encryption functions, PHP also has more comprehensive PHP encryption extension libraries Mcrypt and Mhash.
Among them, the Mcrypt extension library can implement encryption and decryption functions, that is, it can not only encrypt plaintext but also restore ciphertext.
mcrypt is an important encryption support extension library in PHP. In Linux environment: this library is not enabled by default. In window environment: PHP>=5.3, mcrypt extension is enabled by default.

1. Installation of Mcrypt() library

mcypt is a very powerful encryption algorithm extension library. Mcrypt is not installed during the standard PHP installation process, but the libmcrypt.dll file is included in the PHP home directory, so we only need to remove the semicolon in front of extension=php_mcrypt.dll in this line in the PHP configuration file. , and then restart the server to use this extension library.

Supported algorithms and encryption modes

The Mcrypt library supports more than 20 encryption algorithms and 8 encryption modes. The [1] encryption algorithms can be displayed through the functions mcrypt_list_algorithms() and mcrypt_list_modes()
The algorithms supported by Mcrypt are:
cast-128
gost
rijndael-128
twofish
arcfour
cast-256
loki97
rijndael-192
saferplus
wake
blowfish-compat
des
rijndael-256
serpent
xtea
blowfish
enigma
rc2
tripledes
Encryption mode
The encryption modes supported by Mcrypt are:
cbc
cfb
ctr
ecb
ncfb
nofb
ofb
stream
These algorithms and modes should be represented by constants in the application. When writing, add the prefixes MCRYPT_ and MCRYPT_ to represent them, such as the Mcrypt application below

Example

The DES algorithm is represented as MCRYPT_DES;
ECB mode is represented as MCRYPT_MODE_ECB;

Restore: What is my name? I don’t tell most people!

The code is as follows  代码如下 复制代码 $str = "我的名字是？一般人我不告诉他！"; //加密内容 $key = "key:111"; //密钥 $cipher = MCRYPT_DES; //密码类型 $modes = MCRYPT_MODE_ECB; //密码模式 $iv = mcrypt_create_iv(mcrypt_get_iv_size($cipher,$modes),MCRYPT_RAND);//初始化向量 echo "加密明文：".$str." "; $str_encrypt = mcrypt_encrypt($cipher,$key,$str,$modes,$iv); //加密函数 echo "加密密文：".$str_encrypt." "; $str_decrypt = mcrypt_decrypt($cipher,$key,$str_encrypt,$modes,$iv); //解密函数 echo "还原：".$str_decrypt; ?>

Copy code

$str = "What is my name? I won’t tell most people!"; //Encrypted content $key = "key:111"; //Key $cipher = MCRYPT_DES; //Password type $modes = MCRYPT_MODE_ECB; //Password mode $iv = mcrypt_create_iv(mcrypt_get_iv_size($cipher,$modes),MCRYPT_RAND);//Initialization vector echo "Encrypted plain text:".$str." "; $str_encrypt = mcrypt_encrypt($cipher,$key,$str,$modes,$iv); //Encryption function echo "Encrypted ciphertext:".$str_encrypt." "; $str_decrypt = mcrypt_decrypt($cipher,$key,$str_encrypt,$modes,$iv); //Decryption function echo "Restore:".$str_decrypt; ?> Run result: Encrypted plain text: What is my name? I don’t tell most people! Encrypted ciphertext: 锍??]??q???L Laugh ??"? ?

<1> As you can see from the example, before using the PHP encryption extension library Mcrypt to encrypt and decrypt data, an initialization vector, referred to as iv for short, is first created. From $iv = mcrypt_create_iv(mcrypt_get_iv_size($cipher,$modes),MCRYPT_RAND); it can be seen that creating an initialization vector requires two parameters: size specifies the size of iv; source is the source of iv, and the value MCRYPT_RAND is the system random number. <2> The function mcrypt_get_iv_size($cipher,$modes) returns the initialization vector size. The parameters cipher and mode refer to the algorithm and encryption mode respectively. <3> Encryption function $str_encrypt = mcrypt_encrypt($cipher,$key,$str,$modes,$iv); The five parameters of this function are as follows: cipher——encryption algorithm, key——key, data( str)——data to be encrypted, mode——algorithm mode, iv——initialization vector <4> Decryption function mcrypt_decrypt($cipher,$key,$str_encrypt,$modes,$iv); The parameters of this function and the encryption function are almost the same. The only difference is the data, which means that the data needs to be decrypted. The data $str_encrypt, not the original data $str. Note: The parameters cipher, key and mode in the encryption and decryption functions must correspond one to one, otherwise the data cannot be restored Summary mcrypt library constants The Mcrypt library supports more than 20 encryption algorithms and 8 encryption modes. It can be viewed through the functions mcrypt_list_algorithms() and mcrypt_list_modes().