C＃和PHP中的不同MD5文件哈希

Question

I have a small problem in checking MD5 checksum of files in C# and PHP. The hash calculated by PHP script vary from hash calculated by C#.

libcurl.dll C#   = c3506360ce8f42f10dc844e3ff6ed999
libcurl.dll PHP  = f02b47e41e9fa77909031bdef07532af

In PHP I use md5_file function, and my C# code is:

protected string GetFileMD5(string fileName)
{
    FileStream file = new FileStream(fileName, FileMode.Open);
    MD5 md5 = new MD5CryptoServiceProvider();
    byte[] retVal = md5.ComputeHash(file);
    file.Close();

    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < retVal.Length; i++)
    {
        sb.Append(retVal[i].ToString("x2"));
    }
    return sb.ToString();
}

Any ideas how to calculate the same hash? I think that it may be something about encoding.

Thanks in advance!

Answer 1

My C# is rusty, but will:

byte[] retVal = md5.ComputeHash(file);

actually read in the entire file? I think it is just hashing the stream object. I believe you need to read the stream, then hash on the entire file contents?

  int length = (int)file.Length;  // get file length
  buffer = new byte[length];      // create buffer
  int count;                      // actual number of bytes read
  int sum = 0;                    // total number of bytes read

  // read until Read method returns 0 (end of the stream has been reached)
  while ((count = file.Read(buffer, sum, length - sum)) > 0)
      sum += count;  // sum is a buffer offset for next reading
  byte[] retVal = md5.ComputeHash(buffer);

I'm not sure if that actually runs as is, but I think something along those lines will be needed.

Answer 2

I use this:

I havent had yet any issues with comparison of php md5 with c# md5

System.Text.UTF8Encoding text = new System.Text.UTF8Encoding();
System.Security.Cryptography.MD5CryptoServiceProvider md5 = new System.Security.Cryptography.MD5CryptoServiceProvider();                
Convert2.ToBase16(md5.ComputeHash(text.GetBytes(encPassString + sess)));


class Convert2
{
   public static string ToBase16(byte[] input)
   {
      return string.Concat((from x in input select x.ToString("x2")).ToArray());
   }
}