<?php

$key = 'very important data';
function jiami($key, $str)
{
    /* Open module, and create IV */
    $td = mcrypt_module_open('des', '', 'ecb', '');
    //$td = mcrypt_module_open(MCRYPT_DES, '', MCRYPT_MODE_CBC, '');
    //$td = mcrypt_module_open('des', '', 'cbc', '');
    $key = substr($key, 0, mcrypt_enc_get_key_size($td));
    $iv_size = mcrypt_enc_get_iv_size($td);
    $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);

    /* Initialize encryption handle */
    if (mcrypt_generic_init($td, $key, $iv) === -1)
    {
        return FALSE;
    }

    /* Encrypt data */
    $c_t = mcrypt_generic($td, $str);

    /* Clean up */
    mcrypt_generic_deinit($td);
    mcrypt_module_close($td);

    return $c_t;
}

function jiemi($key, $str)
{
    /* Open module, and create IV */
    $td = mcrypt_module_open('des', '', 'ecb', '');
    //$td = mcrypt_module_open(MCRYPT_DES, '', MCRYPT_MODE_CBC, '');
    //$td = mcrypt_module_open('des', '', 'cbc', '');
    $key = substr($key, 0, mcrypt_enc_get_key_size($td));
    $iv_size = mcrypt_enc_get_iv_size($td);
    $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);

    /* Initialize encryption handle */
    if (mcrypt_generic_init($td, $key, $iv) === -1)
    {
        return FALSE;
    }

    /* Reinitialize buffers for decryption */
    $p_t = mdecrypt_generic($td, $str);

    /* Clean up */
    mcrypt_generic_deinit($td);
    mcrypt_module_close($td);

    return trim($p_t);
}

$str = 'hello world!';
echo 'key:' . $key . '<br>';
echo 'str:' . $str . '<br>';

$jiami = jiami($key, $str);
echo '加密:' . $jiami . '<br>';

file_put_contents('jiamiqian.txt', $str);
file_put_contents('jiamihou.txt', $jiami);

$jiemi = jiemi($key, $jiami);
echo '解密:' . $jiemi . '<br>';