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Detailed introduction to the basic use of PHP encryption extension mcrypt

黄舟

Mar 15, 2017 pm 05:14 PM

Mcrypt supports the following four group cipher modes: CBC, OFB, CFB and ECB. If you link with libmcrypt-2.4.x or higher, you can also

support nOFB grouping mode and streaming mode. The following are the supported encryption modes and their corresponding predefined constants.

1. MCRYPT_MODE_ECB (electronic codebook) is suitable for random data. For example, this mode can be used to encrypt other keys. Since the data to be encrypted

is short and random, the shortcomings of this mode actually play a positive role.

2. MCRYPT_MODE_CBC (cipher block chaining) is especially suitable for encrypting files. Compared with ECB, its security is significantly improved.

3. MCRYPT_MODE_CFB (cipher feedback) encrypts each individual byte, so it is very suitable for encryption of byte streams.

4. MCRYPT_MODE_OFB (output feedback, in 8bit) is similar to CFB. It can be used in applications that cannot tolerate the propagation of cryptographic errors. Because

it is encrypted based on 8 bits, so the security factor is low and is not recommended.

5. MCRYPT_MODE_NOFB (output feedback, in nbit) is similar to OFB, but more secure because it can be grouped according to the algorithm specified

size to encrypt the data.

6. MCRYPT_MODE_STREAM is an extended mode that includes stream cipher algorithms such as "WAKE" or "RC4".

<?php
// 获取支持的加密算法
$algos = mcrypt_list_algorithms();
print_r($algos);
 
// 获取所支持的模式
$modes = mcrypt_list_modes();
print_r($modes);

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A few that have been abandoned since PHP5.5.0 Method, no longer recommended to use:

mcrypt_cfc()

mcrypt_cfb()

mcrypt_ecb()

mcrypt_ofb();

##Example 1:

<?php
/**
 * 加密
 * @param $plainText 明文数据
 * @param $key 加密key
 */
function encrypt($plainText, $key) {
    $algo = MCRYPT_RIJNDAEL_256; //加密算法
    $ecb = MCRYPT_MODE_ECB; //加密模式
    $keysize = mcrypt_get_key_size($algo, $ecb);
    $key = substr($key, 0, $keysize); //确保key的长度有效
    $ivSize = mcrypt_get_iv_size($algo, $ecb);
    // 参数 2 可选值有：MCRYPT_RAND（系统随机数生成器）, MCRYPT_DEV_RANDOM（从 /dev/random 文件读取数据）
    // 和 MCRYPT_DEV_URANDOM（从 /dev/urandom 文件读取数据）。在 Windows 平台，PHP 5.3.0 之前的版本中，仅支持 MCRYPT_RAND。 
    // 请注意，在 PHP 5.6.0 之前的版本中， 此参数的默认值为 MCRYPT_DEV_RANDOM。
    $iv = mcrypt_create_iv($ivSize, MCRYPT_RAND); //从随机源创建初始向量
    $encryptText = mcrypt_encrypt($algo, $key, $plainText, $ecb, $iv);
    return trim(base64_encode($encryptText));
}
 
/**
 * 解密
 * @param encryptedText 密文数据
 * @param $key 解密key
 */
function decrypt($encryptedText, $key) {
    $algo = MCRYPT_RIJNDAEL_256;
    $ecb = MCRYPT_MODE_ECB;
    $keysize = mcrypt_get_key_size($algo, $ecb);
    $key = substr($key, 0, $keysize); //确保key的长度有效
    $cryptText = base64_decode($encryptedText);
    $ivSize = mcrypt_get_iv_size($algo, $ecb);
    $iv = mcrypt_create_iv($ivSize, MCRYPT_RAND);
    $decryptText = mcrypt_decrypt($algo, $key, $cryptText, $ecb, $iv);
    return trim($decryptText);
}

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Example 2:

<?php
/**
 * 数据加密
 * @param $plainText 明文数据
 * @param $key 加密key
 */
function encrypt($plainText, $key) {
    $td = mcrypt_module_open(MCRYPT_3DES, &#39;&#39;, &#39;ecb&#39;, &#39;&#39;); // MCRYPT_3DES = tripledes
    $size = mcrypt_enc_get_iv_size($td); // 返回打开的算法的初始向量大小
    $iv = mcrypt_create_iv($size, MCRYPT_RAND); // 从随机源创建初始向量
    $key = substr($key, 0 ,mcrypt_enc_get_key_size($td)); // 打开模式所能支持的最长密钥长度
    // 初始化加密所需的缓冲区
    // 如果发生错误将会返回负数: -3表示密钥长度有误, -4表示内存分配失败, 其他值表示未知错误, 同时会显示对应的警告信息
    $retInt = mcrypt_generic_init($td, $key, $iv);
    $encrypt_data = mcrypt_generic($td, $plainText); //加密
    mcrypt_generic_deinit($td); // 对加密模块进行清理工作
    mcrypt_module_close($td); // 关闭加密模块
    return base64_encode($encrypt_data);
}
 
/**
 * 数据解密
 * @param $encryptData 密文数据
 * @param $key 解密key
 */
function decrypt($encryptData, $key) {
    $encryptData = base64_decode($encryptData);
    $td = mcrypt_module_open(&#39;tripledes&#39;, &#39;&#39;, &#39;ecb&#39;, &#39;&#39;);
    $iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_RAND); //从随机源创建初始向量
    $key = substr($key, 0, mcrypt_enc_get_key_size($td));
    $retInt = mcrypt_generic_init($td, $key, $iv);
    // 请注意，由于存在数据补齐的情况，返回字符串的长度可能和明文的长度不相等
    $plainText = mdecrypt_generic($td, $encryptData); // 解密
    mcrypt_generic_deinit($td); // 对加密模块进行清理工作
    mcrypt_module_close($td); // 关闭加密模块
    return $plainText;
}
 
// 解决数据补齐，造成返回字符串长度和明文长度不一致的问题
$origin_plain = &#39;&#39;; //原始的明文
$plainText = &#39;&#39;; //解密后得到的明文
if (strncmp($origin_plain, $plainText, strlen($origin_plain)) == 0) {
    echo &#39;ok&#39;;
} else {
    echo &#39;error&#39;;
}

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