問題描述

我正在使用 .NET 3.0 類 System.Security.Cryptography.MACTripleDES 類來生成 MAC 值.不幸的是，我正在使用一個(gè)使用1111111111111111"(作為十六進(jìn)制)作為單長(zhǎng) DES 密鑰的硬件設(shè)備.System.Security.Cryptography 庫(kù)會(huì)對(duì)密鑰進(jìn)行一些完整性檢查，如果您嘗試使用加密弱密鑰，則會(huì)返回異常.

I'm using the .NET 3.0 class System.Security.Cryptography.MACTripleDES class to generate a MAC value. Unfortunately, I am working with a hardware device that uses "1111111111111111" (as hex) as a single-length DES key. The System.Security.Cryptography library does some sanity checking on the key and returns a Exception if you try to use a cryptographically weak key.

例如:

byte[] key = new byte[24];
for (int i = 0; i < key.Length; i++)
  key[i] = 0x11;

byte[] data = new byte[] { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
byte[] computedMac = null;
using (MACTripleDES mac = new MACTripleDES(key))
{
  computedMac = mac.ComputeHash(data);
}

拋出異常

System.Security.Cryptography.CryptographicException : Specified key is a known weak key for 'TripleDES' and cannot be used.

我知道這不是安全密鑰.在生產(chǎn)中，設(shè)備將使用新的安全密鑰進(jìn)行閃存.同時(shí)，有什么方法可以抑制這個(gè)異常被拋出?也許是 app.config 或注冊(cè)表設(shè)置?

I know this is not a secure key. In production, the device will be flashed with a new, secure key. In the mean time, is there any way to inhibit this Exception from being thrown? Perhaps an app.config or registry setting?

由于算法強(qiáng)制奇校驗(yàn)，密鑰實(shí)際上是 101010....我不確定這是否適用于 DES 算法，或者只是我所做的支付處理工作中的一個(gè)要求.

The key would actually be 101010... due to the algorithm forcing odd parity. I'm not sure if this is universal to the DES algorithm or just a requirement in the payment processing work I do.

編輯 2:Daniel 在下面的回答中有一些關(guān)于 .NET 黑客的非常好的信息.不幸的是，我無法使用這種技術(shù)解決我的問題，但仍然有一些有趣的閱讀.

Edit 2: Daniel's answer below has some very good information about hacking .NET. Unfortunately, I wasn't able to solve my problem using this technique, but there is still some interesting reading there.

推薦答案

您可以在 DESCryptoServiceProvider.

<1111111111111111> 不是弱 DES 密鑰.

<1111111111111111> is not a weak DES key.

這將計(jì)算一個(gè) DES CBC-MAC:

This will calculate a DES CBC-MAC:

public static byte[] CalcDesMac(byte[] key, byte[] data){
        DESCryptoServiceProvider des = new DESCryptoServiceProvider();
        des.Key = key;
        des.IV = new byte[8];
        des.Padding = PaddingMode.Zeros;
        MemoryStream ms = new MemoryStream();
        using(CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write)){
          cs.Write(data, 0, data.Length);
        }
        byte[] encryption = ms.ToArray();
        byte[] mac = new byte[8];
        Array.Copy(encryption, encryption.Length-8, mac, 0, 8);
        PrintByteArray(encryption);
        return mac;
    }

這篇關(guān)于TripleDES:指定的密鑰是“TripleDES"的已知弱密鑰，不能使用的文章就介紹到這了，希望我們推薦的答案對(duì)大家有所幫助，也希望大家多多支持html5模板網(wǎng)！