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PHP Basics - detailed explanation of DES encryption and decryption in PHP

2022-07-05 01:25:00 【Wild young man】

One 、 brief introduction

DES It's a common symmetric encryption , Its full name is Data Encryption Standard, Data encryption standard , Is a block algorithm using key encryption . The key length is 64 position (bit), Over digit key ignored . The so-called symmetric encryption means that the encryption and decryption keys are the same , Symmetric encryption generally follows a fixed length , Divide the string to be encrypted into blocks , Less than a whole block or at the end of which there are special padding characters .

Cross language DES Encryption and decryption often have problems , Often the filling method is wrong 、 The coding is inconsistent or the encryption and decryption mode is not corresponding .

Fill mode ：pkcs5、pkcs7、iso10126、ansix923、zero.
Encryption mode ：DES-ECB、DES-CBC、DES-CTR、DES-OFB、DES-CFB.
The output type ： No code ,base64 code ,hex code .

As a software developer , It can be tested by tools DES Encryption and decryption , Here's an online tool ：http://tool.chacuo.net/cryptdes

Two 、 Realization

PHP Provides Mcrypt A series of functions to implement DES Encryption and decryption of , But the functions in this extension have been abandoned in succession , since PHP 7.2.0 rise , Will move to PECL.

So this code uses a more general OPENSSL How to achieve DES Encryption and decryption of , The specific implementation and use code are as follows ：

<?php

/**
 * Created by PhpStorm.
 * Title：DES Encryption and decryption class 
 * User: Wanzhou Chen
 * Date: 2022/04/24
 * Time: 22:00
 */

namespace crypt;


class DES
{
    const OUTPUT_NULL = '';
    const OUTPUT_BASE64 = 'base64';
    const OUTPUT_HEX = 'hex';
    /**
     * @var string $method  Encryption and decryption methods , It can be done by  openssl_get_cipher_methods()  get 
     */
    protected $method;
    /**
     * @var string $key  Encryption and decryption key 
     */
    protected $key;

    /**
     * @var string $output  Output format   nothing 、base64、hex
     */
    protected $output;
    /**
     * @var string $iv  Decrypted vector 
     */
    protected $iv;
    /**
     * @var string $options
     */
    protected $options;

    /**
     * DES constructor.
     * @param string $key
     * @param string $method
     *      ECB: DES-ECB、DES-EDE3 （ by  ECB  Mode time ,$iv  If it is empty, you can ）
     *      CBC: DES-CBC、DES-EDE3-CBC、DESX-CBC
     *      CFB: DES-CFB8、DES-EDE3-CFB8
     *      CTR
     *      OFB
     *
     * @param string $output
     *      base64、hex
     *
     * @param string $iv
     * @param int $options
     */
    public function __construct($key, $method = 'DES-ECB', $output = self::OUTPUT_NULL, $iv = '', $options = OPENSSL_RAW_DATA | OPENSSL_NO_PADDING)
    {
        $this->key = $key;
        $this->method = $method;
        $this->output = $output;
        $this->iv = $iv;
        $this->options = $options;
    }

    /**
     *  encryption 
     *
     * @param $str
     * @return string
     */
    public function encrypt($str)
    {
        $str = $this->padding($str, 8);
        $sign = openssl_encrypt($str, $this->method, $this->key, $this->options, $this->iv);

        if ($this->output == self::OUTPUT_BASE64) {
            $sign = base64_encode($sign);
        } else if ($this->output == self::OUTPUT_HEX) {
            $sign = bin2hex($sign);
        }

        return $sign;
    }

    /**
     *  fill 
     *
     * @param $str
     * @param $blockSize
     * @return string
     * @internal param $blocksize
     */
    private function padding($str, $blockSize)
    {
        $pad = $blockSize - (strlen($str) % $blockSize);
        return $str . str_repeat(chr($pad), $pad);
    }

    /**
     *  Decrypt 
     *
     * @param $encrypted
     * @return string
     */
    public function decrypt($encrypted)
    {
        if ($this->output == self::OUTPUT_BASE64) {
            $encrypted = base64_decode($encrypted);
        } else if ($this->output == self::OUTPUT_HEX) {
            $encrypted = hex2bin($encrypted);
        }

        $sign = @openssl_decrypt($encrypted, $this->method, $this->key, $this->options, $this->iv);
        $sign = $this->unPadding($sign);
        $sign = rtrim($sign);
        return $sign;
    }

    /**
     *  To fill in 
     *
     * @param $str
     * @return string
     */
    private function unPadding($str)
    {
        $pad = ord($str{strlen($str) - 1});
        if ($pad > strlen($str)) {
            return false;
        }
        return substr($str, 0, -1 * $pad);
    }

}

Class call

$key = 'key123456';
$iv = 'iv123456';

// DES CBC  encryption 
$des = new DES($key, 'DES-CBC', DES::OUTPUT_BASE64, $iv);
echo $base64Sign = $des->encrypt('Hello DES CBC');
echo "\n";
echo $des->decrypt($base64Sign);
echo "\n";

// DES ECB  encryption 
$des = new DES($key, 'DES-ECB', DES::OUTPUT_HEX);
echo $base64Sign = $des->encrypt('Hello DES ECB');
echo "\n";
echo $des->decrypt($base64Sign);