MD5 Comparing files
There were two ways that this could be done. One was using the Algo provided by .net which is MD5. The code below demostrates using MD5 to calculate the hash value of a Stream using Md5(MD5CryptoServiceProvider) which is found in the System.Security.Cryptography namespace.
1 private static string GetHashString(FileStream fileStream)
2 {
3 string hashString = String.Empty;
4 using (MD5CryptoServiceProvider md5er = new MD5CryptoServiceProvider())
5 {
6 byte[] hash = md5er.ComputeHash(fileStream);
7 foreach (byte hex in hash)
8 {
9 hashString += hex.ToString("x2");
10 }
11 }
12 Debug.Assert(hashString.Length < 200);
13 return hashString;
14 }
You can then use this method to compare the hash of two streams (mostly file streams) . Here is some sample code that does that
1 FileStream file1 = new FileStream("Test.txt", FileMode.Open);
2 file1.Position = 0;
3 string hashValue_1 = GetHashString(file1);
4 Console.Out.WriteLine("hashValue_1 = {0}", hashValue_1);
5 file1.Close();
6
7 FileStream file2 = new FileStream("Copy of Test.txt", FileMode.Open);
8 string hashValue_2 = GetHashString(file2);
9 Console.Out.WriteLine("hashValue_2 = {0}", hashValue_2);
10 file2.Close();
11
12 Console.Out.WriteLine("hashValue_2.Equals(hashValue_1 = {0}",
hashValue_2.Equals(hashValue_1));
13 Console.Read();
Where "Test.txt" and "Copy of Test.txt" have the same contents.
here is the output
Hope this helps someone 
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