lua 與 php 通過AES數據加密進行通訊

近期公司有款《圍住神經貓》的微信小游戲火爆的不行！公司又決定開發一系列的神經貓的小游戲，於是，我被拉過來了。

后來使用cocos-2dx 開發一款小游戲，client用的是lua腳本，為了server與client交互的安全性，我們決定對API接口

傳輸的JSON數據進行加密、解密。普通情況就是client加密，server段進行解密：

luaclient使用的是一個純lua寫的庫：aeslua，下載地址：http://luaforge.net/projects/aeslua/

可是該庫是有問題的：用該庫加密解密是沒有問題的，可是跟PHP通訊就存在問題了，由於該庫加密后base64之后的

字符串PHP是無法解密的！為了這個問題，我查閱了好多資料，最終找到某個國外大神的解決的方法：

http://chainans.blogspot.com/2012/09/working-with-lua-encryption.html（可能有些同學無法FQ，故把原文貼出來例如以下：）

Working with Lua encryption

Recently working with Corona SDK, I start to need some standard encryption/decryption algorithm in Lua. To start with, actually, it has rather small number of developers comparing to the Objective-C which I have been working with. Meaning that there are fewer 3rd party librarys you can rely upon. Luckily, I found one called AESLua which has some code to start. From there, my objective is to make a way to securely passing data between my client and server. (php on server-side) In fact, from what I'd read, my method is not very secure but it is better than nothing. Just for my reference, here are the list of issues along the way

Edited: Tested with iPhone 4... Input cipher text of 1280 characters. Take around 25 seconds. Unacceptable speed for general uses.

1) It requires Lua 5.2 feature which does not seem to be in Corona

Solution: Download LuaBit v0.4 and integrate it... You will need to make a mapping to allow API call to the proper place

2) Next you need to get Base64 library -- grab it here https://gist.github.com/2563975 -- It initially made to allow passing it over the URL (using '-' and '_' instead of '+' and '/') So, I change them to the latter one.

3) For AESLua, by default, it uses AES-128, CBC, some kind of random padding <- I don't know its name, IV = 0. I will change it into is AES-128, CBC, PKCS7 padding. Here are the website to test if our conversion is ok or not

http://www.unsw.adfa.edu.au/~lpb/src/AEScalc/AEScalc.html

http://www.tools4noobs.com/online_tools/decrypt/

Here are the things to do

3.1) In pwInKey function, comment the line out

password = ciphermode.encryptString(pwBytes, password, ciphermode.encryptCBC);

3.2) In util.padByteString function, change it to

local paddingLength = math.ceil(#data/16)*16 - #data;

local padding = "";

local paddingValue = string.char ( paddingLength ) -- PKCS7 padding

for i=1,paddingLength do

padding = padding .. paddingValue; -- PKCS7 padding

end

return data .. padding;

4) Set up web server for testing, you will need php / mcrypt mod to test.

5) Creating a php for testing... here is a code

Now, my plain text below is "1234567890123456ss@#%de".

<?php

$data = 'dXzNDNxckOrb7uz2ON0AAJp4BXgkYewblTNWBSAQSEw=';

$key128 = '1234567890123456';

$iv = '\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0';

echo mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key128, base64_decode($data), MCRYPT_MODE_CBC, $iv)

That's it. The encryption backward to client machine should be a piece of cake. =)

*** By using these library, the user should be aware of the fact that Lua's performance is still far from native code. You may not want to use this algorithm to encrypt a large volume of data.

依照他的辦法，一切都OK了。可是有下面幾點須要說明下面：（本人摸索的）

1.利用CBC模式加密的字符串的key必須是16位，否則PHP無法解密！

3.上面文章中沒有把unpack函數寫出來，本人查閱了一些資料，補充了，否則aeslua無法正常解密了！

function public.unpadByteString(data)
local padLength = tonum((string.byte(data, #data)));
return string.sub(data,1, #data-padLength) --unpack
end

lua 與 php 通過AES數據加密進行通訊

Working with Lua encryption

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