php des 加密解密實例

des加密是對稱加密中在互聯網應用的比較多的一種加密方式，php 通過mcrypt擴展庫來支持des加密，要在Php中使用des加密，需要先安裝mcrypt擴展庫

下面是加密解密的實例

$iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
$iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
$key = "This is a very secret key";//密鑰
$text = "Meet me at 11 o'clock behind the monument.";//需要加密的內容
echo ($text) . "\n";

$crypttext =base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $text, MCRYPT_MODE_ECB, $iv));
echo $crypttext . "\n";//加密后的內容
echo mcrypt_decrypt(MCRYPT_RIJNDAEL_256,$key,base64_decode($crypttext),MCRYPT_MODE_ECB,$iv);//解密后的內容</pre> 

 


在AES加密算法中通常會用到MCRYPT_RIJNDAEL_128、MCRYPT_RIJNDAEL_192、MCRYPT_RIJNDAEL_256三種，后面的128、192、256代表的是秘鑰（也就是加密的Key）是多少bit的，比如使用的是MCRYPT_RIJNDAEL_128，那么用這個算法加密時秘鑰長度就是128bit的，比如 $key = 'fjjda0&9^$$#+*%$fada'，是20個字符，那在實際加密的時候只用到前16個字符加密（16*8=128）,不足128bit的php中會用'\0'來補齊。


 

有的時候做項目對接的時候，可能你用的是Php加密的，而對方用的是java寫的，對接的過程中就發現機加密后的內容對方解密不了，這是因為Php跟java在實現這個算法的時候有差別，要想正確加密解密需要兩邊都做下處理：

PHP:

<?php
class Security {
    public static function encrypt($input, $key) {
        $size = mcrypt_get_block_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_ECB);
        $input = Security::pkcs5_pad($input, $size);
        $td = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_ECB, '');
        $iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
        mcrypt_generic_init($td, $key, $iv);
        $data = mcrypt_generic($td, $input);
        mcrypt_generic_deinit($td);
        mcrypt_module_close($td);
        $data = base64_encode($data);
        return $data;
    }


private static function pkcs5_pad ($text, $blocksize) {
    $pad = $blocksize - (strlen($text) % $blocksize);
    return $text . str_repeat(chr($pad), $pad);
}

public static function decrypt($sStr, $sKey) {
    $decrypted= mcrypt_decrypt(
    MCRYPT_RIJNDAEL_128,
    $sKey,
    base64_decode($sStr),
    MCRYPT_MODE_ECB
);

    $dec_s = strlen($decrypted);
    $padding = ord($decrypted[$dec_s-1]);
    $decrypted = substr($decrypted, 0, -$padding);
    return $decrypted;
}   

}
$key = "1234567891234567";
$data = "example";
$value = Security::encrypt($data , $key );
echo $value.'<br/>';
echo Security::decrypt($value, $key );</pre> 

 Java:
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;
public class Security {
    public static String encrypt(String input, String key){
        byte[] crypted = null;
        try{
            SecretKeySpec skey = new SecretKeySpec(key.getBytes(), "AES");
            Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
            cipher.init(Cipher.ENCRYPT_MODE, skey);
            crypted = cipher.doFinal(input.getBytes());
        }catch(Exception e){
        System.out.println(e.toString());
    }
    return new String(Base64.encodeBase64(crypted));
}

public static String decrypt(String input, String key){
    byte[] output = null;
    try{
        SecretKeySpec skey = new SecretKeySpec(key.getBytes(), "AES");
        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, skey);
        output = cipher.doFinal(Base64.decodeBase64(input));
        }catch(Exception e){
        System.out.println(e.toString());
    }
    return new String(output);
}

public static void main(String[] args) {
    String key = "1234567891234567";
    String data = "example";

    System.out.println(Security.encrypt(data, key));

    System.out.println(Security.decrypt(Security.encrypt(data, key), key));


}   

}</pre>