Calculate the Hash of the Contents of a File in C#? [duplicate]

Question

I need to calculate the Hash of the Contents of a File in C#? So, that I can compare two file hashes in my app. I have search but not found.

Answer 1

You could use MD5CryptoServiceProvider, which will work with text based files as well as binary files.

byte[] myFileData = File.ReadAllBytes(myFileName);
byte[] myHash = MD5.Create().ComputeHash(myFileData);

Or... if you work with large files and do not want to load the whole file into memory:

byte[] myHash;
using (var md5 = MD5.Create())
using (var stream = File.OpenRead(myFileName))
    myHash = md5.ComputeHash(stream);

You can compare to byte arrays from two files with Enumerable.SequenceEqual:

myHash1.SequenceEqual(myHash2); 

You could also try to create an CRC-calculator. See: http://damieng.com/blog/2006/08/08/calculating_crc32_in_c_and_net

Answer 2

You should search better ;)

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


protected string GetMD5HashFromFile(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();
}

Pass your file to this function like this.

GetMD5HashFromFile("text1.txt");
GetMD5HashFromFile("text2.txt");