C＃和Java - hmacsha256哈希的区别 [英] c# and java - difference between hmacsha256 hash

问题描述

我在Java中的以下代码：

I have the following code in Java:

byte[] secretKey = secretAccessKey.getBytes("UTF-8");
SecretKeySpec signingKey = new SecretKeySpec(secretKey, "HmacSHA256");
Mac mac = Mac.getInstance("HmacSHA256");
mac.init(signingKey);
byte[] bytes = data.getBytes("UTF-8");
byte[] rawHmac = mac.doFinal(bytes);
String result = javax.xml.bind.DatatypeConverter.printBase64Binary(rawHmac);

和C＃中的以下代码：

UTF8Encoding enc = new UTF8Encoding();
byte[] secretKey = enc.GetBytes(secretAccessKey);
HMACSHA256 hmac = new HMACSHA256(secretKey);
hmac.Initialize();
byte[] bytes = enc.GetBytes(data);
byte[] rawHmac = hmac.ComputeHash(bytes);
string result = Convert.ToBase64String(rawHmac);

字节数组SecretKey的和字节是等价的，但该字节数组rawHmac不同以及字符串结果是不同的。 ？任何人都可以看到，为什么

The byte arrays "secretKey" and "bytes" are equivalent but the byte array "rawHmac" is different, and the string "result" is different. Can anyone see why?

推荐答案

不这样做：

byte[] bytes = data.getBytes();

这将使用平台默认的编码字符串转换为字节数组。能而你想要的东西可重复的平台之间变化。我建议UTF-8：

That will use the platform default encoding to convert a string to a byte array. That can vary between platform, whereas you want something repeatable. I would suggest UTF-8:

byte[] bytes = data.getBytes("UTF-8");

（做的关键是相同的，当然。）

(Do the same for the key, of course.)

您应该然后使用相同的编码在C＃ - 的不的ASCII，除非你真的想不处理非ASCII字符

You should then use the same encoding in your C# - not ASCII, unless you really want to not handle non-ASCII characters.

byte[] bytes = Encoding.UTF8.GetBytes(data);

这也不清楚怎么你算账对比结果 - 不要忘记，字节在Java的签名，但在C＃中的无符号。它可能是最简单的哈希转换为十六进制或Base64出于比较的目的

It's also not clear how you're comparing the results afterwards - don't forget that byte is signed in Java, but unsigned in C#. It's probably simplest to convert the hash to hex or base64 for comparison purposes.

编辑：我强烈怀疑的最后一部分是问题 - 对比结果

I strongly suspect the last part was the problem - comparing the results.

下面是两个短，但完整的程序（使用Java中的base64 iharder.net转换器）以下生产同类的base64输出：

Here are two short but complete programs (using the iharder.net base64 converter in Java) which produce the same base64 output:

Java的：

import java.util.*;
import javax.crypto.*;
import javax.crypto.spec.*;

public class Test {
    public static void main (String[] args) throws Exception {
        String secretAccessKey = "mykey";
        String data = "my data";
        byte[] secretKey = secretAccessKey.getBytes();
        SecretKeySpec signingKey = new SecretKeySpec(secretKey, "HmacSHA256");
        Mac mac = Mac.getInstance("HmacSHA256");
        mac.init(signingKey);
        byte[] bytes = data.getBytes();
        byte[] rawHmac = mac.doFinal(bytes);
        System.out.println(Base64.encodeBytes(rawHmac));
    }
}

C＃：

C#:

using System;
using System.Security.Cryptography;
using System.Text;

class Test
{
    static void Main()
    {
        String secretAccessKey = "mykey";
        String data = "my data";
        byte[] secretKey = Encoding.UTF8.GetBytes(secretAccessKey);
        HMACSHA256 hmac = new HMACSHA256(secretKey);
        hmac.Initialize();
        byte[] bytes = Encoding.UTF8.GetBytes(data);
        byte[] rawHmac = hmac.ComputeHash(bytes);
        Console.WriteLine(Convert.ToBase64String(rawHmac));
    }
}

这两个输出：

ivEyFpkagEoghGnTw/LmfhDOsiNbcnEON50mFGzW9/w=

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