解码错误的结果

本文关键字：结果 错误 解码 | 更新日期: 2023-09-27 18:13:41

我需要在c#中创建一个哈希签名。

伪代码的例子，我需要在我的c#代码实现:

Signatur(Request) = new String(encodeBase64URLCompatible(HMAC-SHA-256(getBytes(Z, "UTF-8"), decodeBase64URLCompatible(getBytes(S, "UTF-8")))), "UTF-8")

Z: apiSecretS: stringToSign

expectedSignatur和apiSecret的编码为Base64 URL Encoding [RFC 4648 Section 5]

我的问题是我总是得到错误的结果。

public static string Base64Decode(string base64EncodedData)
{
    var base64EncodedBytes = Convert.FromBase64String(base64EncodedData);
    return Encoding.UTF8.GetString(base64EncodedBytes);
}
public static string Base64Encode(string plainText)
{
    var plainTextBytes = Encoding.UTF8.GetBytes(plainText);
    return Convert.ToBase64String(plainTextBytes);
}
private static byte[] HmacSha256(string data, string key)
{
     using (var hmac = new HMACSHA256(Encoding.UTF8.GetBytes(key)))
     {
       return hmac.ComputeHash(Encoding.UTF8.GetBytes(data));
     }
}
static void Main(string[] args)
{
     var apiSecret = "JrXRHCnUegQJAYSJ5J6OvEuOUOpy2q2-MHPoH_IECRY=";
     var stringToSign = "f3fea5f3-60af-496f-ac3e-dbb10924e87a:20160201094942:e81d298b-60dd-4f46-9ec9-1dbc72f5b5df:Qg5f0Q3ly1Cwh5M9zcw57jwHI_HPoKbjdHLurXGpPg0yazdC6OWPpwnYi22bnB6S";
     var expectedSignatur = "ps9MooGiTeTXIkPkUWbHG4rlF3wuTJuZ9qcMe-Y41xE=";
     apiSecret = apiSecret.Replace('-', '+').Replace('_', '/').PadRight(apiSecret.Length + (4 - apiSecret.Length % 4) % 4, '=');
     var secretBase64Decoded = Base64Decode(apiSecret);
     var hmac = Convert.ToBase64String(HmacSha256(secretBase64Decoded, stringToSign));
     var signatur = hmac.Replace('+', '-').Replace('/', '_');

     Console.WriteLine($"signatur: {signatur}");
     Console.WriteLine($"expected: {expectedSignatur}");
     Console.WriteLine(signatur.Equals(expectedSignatur));
     Console.ReadLine();
 }

解码错误的结果

您假设您的密钥最初是用UTF-8编码的文本-但看起来不是这样。您应该将逻辑二进制数据保持为二进制数据—您根本不需要Base64Encode和Base64Decode方法。相反，您的HmacSha256方法应该将byte[]作为密钥，并且您可以使用Convert.FromBase64String从base64编码的秘密中获取这些字节:

using System;
using System.Text;
using System.Security.Cryptography;
class Test
{    
    private static byte[] HmacSha256(byte[] key, string data)
    {
        using (var hmac = new HMACSHA256(key))
        {
            return hmac.ComputeHash(Encoding.UTF8.GetBytes(data));
        }
    }
    static void Main(string[] args)
    {
        var apiSecret = "JrXRHCnUegQJAYSJ5J6OvEuOUOpy2q2-MHPoH_IECRY=";
        var stringToSign = "f3fea5f3-60af-496f-ac3e-dbb10924e87a:20160201094942:e81d298b-60dd-4f46-9ec9-1dbc72f5b5df:Qg5f0Q3ly1Cwh5M9zcw57jwHI_HPoKbjdHLurXGpPg0yazdC6OWPpwnYi22bnB6S";
        var expectedSignatur = "ps9MooGiTeTXIkPkUWbHG4rlF3wuTJuZ9qcMe-Y41xE=";
        apiSecret = apiSecret.Replace('-', '+').Replace('_', '/').PadRight(apiSecret.Length + (4 - apiSecret.Length % 4) % 4, '=');
        var secretBase64Decoded = Convert.FromBase64String(apiSecret);
        var hmac = Convert.ToBase64String(HmacSha256(secretBase64Decoded, stringToSign));
        var signatur = hmac.Replace('+', '-').Replace('/', '_');
        Console.WriteLine($"signatur: {signatur}");
        Console.WriteLine($"expected: {expectedSignatur}");            
        Console.WriteLine(signatur.Equals(expectedSignatur));
    }
}

我个人会改变你的HmacSha256方法为:

private static byte[] ComputeHmacSha256Hash(byte[] key, byte[] data)
{
    using (var hmac = new HMACSHA256(key))
    {
        return hmac.ComputeHash(data);
    }
}

以便更通用，为了方便起见，可以在编码为UTF-8后添加另一个方法来计算哈希值。这样就可以对任何数据签名，而不仅仅是字符串。

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