php 3des加密解密類程式碼

3DES（或稱為Triple DES）是三重資料加密演算法（TDEA，Triple Data Encryption Algorithm）塊密碼的通稱。它相當於是對每個資料區塊應用三次DES密碼編譯演算法。由於電腦運算能力的增強，原版DES密碼的密鑰長度變得容易被暴力破解；3DES即是設計用來提供一種相對簡單的方法，即通過增加DES的密鑰長度來避免類似的攻擊，而不是設計一種全新的塊密碼演算法。

代碼如下

複製代碼

<?php class Crypt3Des { var $key; function Crypt3Des($key){ $this->key = $key; } function encrypt($input){ $size = mcrypt_get_block_size(MCRYPT_3DES,'ecb'); $input = $this->pkcs5_pad($input, $size); $key = str_pad($this->key,24,'0'); $td = mcrypt_module_open(MCRYPT_3DES, '', '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($this->PaddingPKCS7($data)); $data = base64_encode($data); return $data; } function decrypt($encrypted){ $encrypted = base64_decode($encrypted); $key = str_pad($this->key,24,'0'); $td = mcrypt_module_open(MCRYPT_3DES,'','ecb',''); $iv = @mcrypt_create_iv(mcrypt_enc_get_iv_size($td),MCRYPT_RAND); $ks = mcrypt_enc_get_key_size($td); @mcrypt_generic_init($td, $key, $iv); $decrypted = mdecrypt_generic($td, $encrypted); mcrypt_generic_deinit($td); mcrypt_module_close($td); $y=$this->pkcs5_unpad($decrypted); return $y; } function pkcs5_pad ($text, $blocksize) { $pad = $blocksize - (strlen($text) % $blocksize); return $text . str_repeat(chr($pad), $pad); } function pkcs5_unpad($text){ $pad = ord($text{strlen($text)-1}); if ($pad > strlen($text)) {    return false; } if (strspn($text, chr($pad), strlen($text) - $pad) != $pad){    return false; } return substr($text, 0, -1 * $pad); } function PaddingPKCS7($data) { $block_size = mcrypt_get_block_size(MCRYPT_3DES, MCRYPT_MODE_CBC); $padding_char = $block_size - (strlen($data) % $block_size); $data .= str_repeat(chr($padding_char),$padding_char); return $data; } } 用法: $crypt = new Crypt3Des('密鑰'); $a = '待加密字串'; $code = $crypt->encrypt($a);//加密 echo $crypt->decrypt($code);//解密