php 3DES|DES 加密解密，通用

<?php
//set_include_path(get_include_path().PATH_SEPARATOR.'phpseclib');
include('Crypt/DES.php');

$des = new Crypt_DES();

$des->setKey('abcdefgh');
$plaintext = 'a';
$jiami = base64_encode($des->encrypt($plaintext));
echo "Encode:".$jiami."<br/>";
echo "Decode:".$des->decrypt(base64_decode($jiami));
?>&nbsp;

由于PHP使用mcrypt扩展进行3DES加密，填充模式是跟JAVA以及.NET是不一样的，JAVA和.NET填充模式使用的是PKCS7。

所以PHP端必须自定义一个函数对加密字符串进行PKCS7模式补位填充 。

另外一点就是双方的KEY注意进行base64编码，最后PHP端经过3DES加密后得到的结果也需要进行base64编码。

以上几点都做好之后，加密结果就一致了。

<?php
class STD3Des
{
    private $key = "";
    private $iv = "";

    /**
     * 构造，传递二个已经进行base64_encode的KEY与IV
     *
     * @param string $key
     * @param string $iv
     */
    function __construct($key, $iv)
    {
        if (empty($key) || empty($iv)) {
            echo 'key and iv is not valid';
            exit();
        }
        $this->key = $key;
        $this->iv = $iv;
    }

    /**
     *加密
     * @param <type> $value
     * @return <type>
     */
    public function encrypt($value)
    {
        $td = mcrypt_module_open(MCRYPT_3DES, '', MCRYPT_MODE_CBC, '');
        $iv = base64_decode($this->iv);
        $value = $this->PaddingPKCS7($value);
        $key = base64_decode($this->key);
        mcrypt_generic_init($td, $key, $iv);
        $ret = base64_encode(mcrypt_generic($td, $value));
        mcrypt_generic_deinit($td);
        mcrypt_module_close($td);
        return $ret;
    }

    /**
     *解密
     * @param <type> $value
     * @return <type>
     */
    public function decrypt($value)
    {
        $td = mcrypt_module_open(MCRYPT_3DES, '', MCRYPT_MODE_CBC, '');
        $iv = base64_decode($this->iv);
        $key = base64_decode($this->key);
        mcrypt_generic_init($td, $key, $iv);
        $ret = trim(mdecrypt_generic($td, base64_decode($value)));
        $ret = $this->UnPaddingPKCS7($ret);
        mcrypt_generic_deinit($td);
        mcrypt_module_close($td);
        return $ret;
    }

    private function PaddingPKCS7($data)
    {
        $block_size = mcrypt_get_block_size('tripledes', 'cbc');
        $padding_char = $block_size - (strlen($data) % $block_size);
        $data .= str_repeat(chr($padding_char), $padding_char);
        return $data;
    }

    private function UnPaddingPKCS7($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);
    }
}

//使用
include('STD3Des.class.php');
$key = 'abcdefgh';
$iv = 'abcdefgh';
$msg = 'test string';
$des = new STD3Des(base64_encode($key), base64_encode($iv));
$rs1 = $des->encrypt($msg);
echo $rs1 . '<br />';
$rs2 = $des->decrypt($rs1);
echo $rs2;
?>