c# md5 and php md5 not match

Question

here is my c# compute signature code

using System;
using System.Text;

public class Test
{
    public static void Main()
    {
    string str;
    string syskey = "123456789";
    str = GenSignature(syskey,"foo","20170426001757");
    Console.WriteLine(str);
}

public static string GenSignature(string syskey,params string[] paramValues)
    {
        string source = "";
        for (int i = 0; i < paramValues.Length; i++)
        {
            if (!string.IsNullOrEmpty(paramValues[i]))
            {
                source += (string.IsNullOrEmpty(source) ? "" : "&") + paramValues[i];
            }
        }

        if (string.IsNullOrEmpty(source))
        {
            return "";
        }

        source +=  "&" + syskey;
        // Debug.WriteLine(source);
        using (System.Security.Cryptography.MD5 m = System.Security.Cryptography.MD5.Create())
        {
            byte[] hashData = m.ComputeHash(UTF8Encoding.UTF8.GetBytes(source));
            return BitConverter.ToString(hashData).Replace("-", "").ToUpper();
        }
    }
}

and the php get signature code is below:

function getSignature() {
    $syskey = "123456789";
    $sysCode =  "foo";
    $timeStamp = "20170426001757";
    $str = "&".$sysCode."&".$timeStamp."&".$syskey;
    return strtoupper(md5($str));
}
echo getSignature();

I do not know c# very well, but the result I get are totally different, Did any one know the two languages and tell me something, Thanks a lot.

Answer 1

In the PHP example you prepend every part with an ampersand (&), however in the C# version you prepend every part but the first:

source += (string.IsNullOrEmpty(source) ? "" : "&") + paramValues[i];

string.IsNullOrEmpty(source) will return true the first time since you initially set source to "", thus an ampersand won't get added in the very beginning of the string.

Change your code to this and it should work:

source += "&" + paramValues[i];

Online test: https://dotnetfiddle.net/KhoFtL