// 加密
function encryptStr($str, $key){
    $block = mcrypt_get_block_size('des', 'ecb');
    $pad = $block - (strlen($str) % $block);
    $str .= str_repeat(chr($pad), $pad);
    $enc_str = mcrypt_encrypt(MCRYPT_DES, $key, $str, MCRYPT_MODE_ECB);
    return base64_encode($enc_str);
}


// 解密
function decryptStr($str, $key){
    $str = base64_decode($str);
    $str = mcrypt_decrypt(MCRYPT_DES, $key, $str, MCRYPT_MODE_ECB);
    $block = mcrypt_get_block_size('des', 'ecb');
    $pad = ord($str[($len = strlen($str)) - 1]);
    return substr($str, 0, strlen($str) - $pad);
}