使用 Python 创建 WPA 消息完整性代码 (MIC) [英] Creating WPA Message Integrity Code (MIC) with Python

问题描述

我试图计算 WPA 握手数据包的 MIC，但不幸的是它失败了.更准确地说，我采用了 802.1x 数据包(如规范所述).

I tried to calculate the MIC for a WPA Handshake packet, but unfortunatelly it fails. To be more precise, I took the 802.1x packet (like the specification says).

MIC = HMAC_MD5(MIC Key, 16, 802.1x data)

这是相关代码:

mic = hmac.new(ptk[0:16],data)
print "mic: " + mic.hexdigest()  + "\n"

其中 hmac.new 取自 hmac 库:

Where hmac.new is taken from the hmac lib:

import hmac,hashlib,binascii

用于加密的密钥显然由 Pairwise Transcient Key(所谓的 Key Confirmation Key)的前 16 个字节组成.PTK 由名为 cowPatty 的程序确认.所以我可以排除这两个因素是错误的.这是我的802.1x数据，由十六进制值0103引入:

The key for the encryption consists obviously of the first 16 bytes of the Pairwise Transcient Key (the so called Key Confirmation Key). The PTK is confirmed by a program called cowPatty. So I can exclude these two factors to be wrong. This is my 802.1x data, which is introduced by the hex values 0103:

01030077fe010a001000000000000000
01ae11df37f5fb100665ce0c849f5950
c0e7901da3224ddfc9e9434babad5512
73000000000000000000000000000000
00000000000000000000000000000000
00e8b4b90bfc3fd97b657afeb66262ae
940018dd160050f20101000050f20201
000050f20401000050f202

Wireshark 计算的 MIC 为:

The MIC that Wireshark calculates is:

e8b4b90bfc3fd97b657afeb66262ae94

我计算的 MIC 是:

The MIC that I calculate is:

5492624bb538b52d6aa6261c692bd595

不幸的是，我做什么并不重要，我永远无法计算相同的 MIC.也许一些专家有宝贵的意见，那真的很感激！

Unfortunatelly it doesn't matter what I do, I am never be able to compute the same MIC. Maybe some expert has valuable input, that really would be appreciated!

最好的问候！

推荐答案

以下是 4 次握手中第二条消息的 EAPOL 数据(在逻辑链路控制之后开始):

Here is the EAPOL data (starting right after the Logical-Link Control) from the second message in a 4 way handshake:

unsigned char eapol[] =
{
    '\x01',        // Version
    '\x03',        // Type
    '\x00','\x77', // Length
    '\xfe',        // Key Descriptor Type
    '\x01','\x0a', // Key information
    '\x00','\x10', // Key length
    // Replay counter
    '\x00','\x00','\x00','\x00','\x00','\x00','\x00','\x01',
    // WPA Key Nounce
    '\x77','\xd6','\x54','\xad','\x0c','\x1f','\xea','\x2f',
    '\x20','\x99','\xf1','\xdd','\x1c','\xae','\xdb','\xd8',
    '\xf7','\xe8','\x86','\xb0','\x81','\x60','\xed','\x7f',
    '\x70','\xdd','\xbb','\x33','\xb6','\xf1','\xd9','\x98',
    // Key IV
    '\x00','\x00','\x00','\x00','\x00','\x00','\x00','\x00',
    '\x00','\x00','\x00','\x00','\x00','\x00','\x00','\x00',
    // Key RSC
    '\x00','\x00','\x00','\x00','\x00','\x00','\x00','\x00',
    // Key ID
    '\x00','\x00','\x00','\x00','\x00','\x00','\x00','\x00',
    // MIC **************** CHANGE HERE ********************
//  '\x0a','\x62','\x24','\x07','\x11','\x36','\xd5','\x67',
//  '\x87','\xc0','\x7b','\x82','\x6b','\x06','\xf7','\xff',
    '\x00','\x00','\x00','\x00','\x00','\x00','\x00','\x00',
    '\x00','\x00','\x00','\x00','\x00','\x00','\x00','\x00',
    // Key Data Length
    '\x00','\x18',
    // Key Data
    '\xdd','\x16','\x00','\x50','\xf2','\x01','\x01','\x00',
    '\x00','\x50','\xf2','\x04','\x01','\x00','\x00','\x50',
    '\xf2','\x04','\x01','\x00','\x00','\x50','\xf2','\x02'
};

确保将 MIC 字段的 16 个字节替换为\x00"，并且您将准备好根据 Michael 算法计算的有效 EAPOL 数据.

Make sure you replace the 16 bytes of MIC field by '\x00' and you'll have a valid EAPOL data ready to be calculated against Michael algorithm.

另外，请确保您使用的是基于 WPA 版本的正确算法.WPA1 使用 HMAC 和 MD5 哈希函数，WPA2 使用 HMAC 和 SHA1 哈希，正如你在 aircrack-ng 源码中看到的:

Also, make sure you're using the right algorithm based on WPA version. WPA1 uses HMAC with MD5 hash function, WPA2 uses HMAC with SHA1 hash, as you can see in aircrack-ng source:

if (ap->wpa.keyver == 1)
    HMAC(EVP_md5(), ptk[j], 16, ap->wpa.eapol, ap->wpa.eapol_size, mic[j], NULL);
else
    HMAC(EVP_sha1(), ptk[j], 16, ap->wpa.eapol, ap->wpa.eapol_size, mic[j], NULL);

我认为 python 在 HMAC 对象中默认使用 MD5.

I think python uses MD5 by default in HMAC object.

这篇关于使用 Python 创建 WPA 消息完整性代码 (MIC)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！