我的哈希值错误? C#密码学

问题描述

我的文本文件说，快速的棕色狐狸跳过了那只懒狗，但是，当我尝试从该文件中获取哈希值时，md5和sha1都与维基百科的结果不同.我有3个问题. 1)我在代码中做错了什么? 2)我怎样才能使这段代码更好? (我需要初始化)3)如何加盐吗?

My text file says The quick brown fox jumps over the lazy dog, however when i try to get the hash from this file both the md5 and sha1 is different from the wikipedias result. I have 3 questions. 1) What did i do wrong in the code? 2) How can i have this piece of code better? (do i need the Initialize) 3) How do i salt this?

    {
        const int bufSize = 1024 * 8;
        int read;
        byte[] buf = new byte[bufSize];
        string fn = @"b.txt";
        byte[] result1 = new byte[0];
        byte[] result2 = new byte[0];
        SHA1 sha = new SHA1CryptoServiceProvider();
        MD5  md5 = new MD5CryptoServiceProvider();
        sha.Initialize();
        md5.Initialize();
        FileStream fin = File.OpenRead(fn);
        while ((read = fin.Read(buf, 0, buf.Length)) != 0)
        {
            result1 = sha.ComputeHash(buf);
            result2 = md5.ComputeHash(buf);
        }
        fin.Close();
        MessageBox.Show(myFunc(result1));
        MessageBox.Show(myFunc(result2));
    }

推荐答案

(现在处理哈希算法.我怀疑这是不必要的，但这是一个好习惯:)

( Disposing of the hash algorithms now. I suspect it's unnecessary, but it's good practice :)

您正在为整个缓冲区调用ComputeHash，即使您应该仅对已读取的缓冲区的一部分进行哈希处理.此外，您正在为每次对Read的调用计算一个新的哈希值.

You're calling ComputeHash for the whole buffer even though you should only be hashing the portion of the buffer you've read. In addition, you're computing a new hash for each call to Read.

以下是一些非常简单的代码来计算哈希:

Here's some really simple code to compute the hashes:

using System;
using System.IO;
using System.Security.Cryptography;

class Test
{
    static void Main()
    {
        byte[] plaintext = File.ReadAllBytes("b.txt");
        using (MD5 md5 = MD5.Create())
        {
            byte[] md5Hash = md5.ComputeHash(plaintext);
            Console.WriteLine(BitConverter.ToString(md5Hash));
        }

        using (SHA1 sha1 = SHA1.Create())
        {
            byte[] sha1Hash = sha1.ComputeHash(plaintext);
            Console.WriteLine(BitConverter.ToString(sha1Hash));
        }
    }
}

这给出了维基百科的结果-请注意，b.txt末尾不应包含换行符.

This gives the results as per wikipedia - note that b.txt shouldn't have a newline at the end of it.

获取二进制数据开始的另一种方法是:

An alternative way of getting the binary data to start with would be:

byte[] plaintext = Encoding.ASCII.GetBytes(
    "The quick brown fox jumps over the lazy dog");

请注意，这只是一次计算哈希的简单方法.如果要以流方式进行操作(即在其中读取一些数据，将其添加到哈希中，读取一些其他数据等)，则可以使用 ComputeHash(Stream) 重载，或者(如果您想向其中推送"数据)您可以使用TransformBlock和TransformFinalBlock，例如这个:

Note that this is just the simple way of computing a hash in one go. If you want to do it in a streaming fashion (i.e. where you read some data, add it to the hash, read some more data etc) then either you can use the ComputeHash(Stream) overload or (if you want to "push" data to it) you can use TransformBlock and TransformFinalBlock, like this:

using System.Text;

class Test
{
    static void Main()
    {
        using (MD5 md5 = MD5.Create())
        using (SHA1 sha1 = SHA1.Create())
        using (Stream input = File.OpenRead("b.txt"))
        {
            // Artificially small to make sure there's
            // more than one read
            byte[] buffer = new byte[4];
            int bytesRead;

            while ((bytesRead = input.Read(buffer, 0, buffer.Length)) > 0)
            {
                md5.TransformBlock(buffer, 0, bytesRead, null, 0);
                sha1.TransformBlock(buffer, 0, bytesRead, null, 0);
            }
            md5.TransformFinalBlock(buffer, 0, 0);
            sha1.TransformFinalBlock(buffer, 0, 0);

            Console.WriteLine(BitConverter.ToString(md5.Hash));
            Console.WriteLine(BitConverter.ToString(sha1.Hash));
        }
    }
}

请注意我们将null传递给TransformBlock的方式，因为我们不需要任何输出，并且我们也不会在最终块中转换任何数据.根据先前的评论，我怀疑这是您要使用的示例.

Note the way we pass null to TransformBlock because we don't need any output, and we don't transform any data in the final block. I suspect this is the example you'll want to use, based on your previous comments.

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