How do I create an MD5 hash digest from a text file?

Question

Using C#, I want to create an MD5 hash of a text file. How can I accomplish this?

Update: Thanks to everyone for their help. I\'ve finally settled u

Answer 1

Short and to the point. filename is your text file's name:

using (var md5 = MD5.Create())
{
    return BitConverter.ToString(md5.ComputeHash(File.ReadAllBytes(filename))).Replace("-", "");
}

Answer 2

Here is a .NET Standard version that doesn't require reading the entire file into memory:

    private byte[] CalculateMD5OfFile(FileInfo targetFile)
    {
        byte[] hashBytes = null;
        using (var hashcalc = System.Security.Cryptography.MD5.Create())
        {
            using (FileStream inf = targetFile.OpenRead())
                hashcalc.ComputeHash(inf);
            hashBytes = hashcalc.Hash;
        }
        return hashBytes;
    }

You can convert the byte[] array into a string using the methods shown above. Also: You can change "MD5" in the third line to SHA1, SHA256, etc. to calculate other hashes.

Answer 3

internal static string GetHashCode(string filePath, HashAlgorithm cryptoService)
{
// create or use the instance of the crypto service provider
// this can be either MD5, SHA1, SHA256, SHA384 or SHA512
using (cryptoService)
{
    using (var fileStream = new FileStream(filePath, 
                                           FileMode.Open, 
                                           FileAccess.Read, 
                                           FileShare.ReadWrite))
    {
        var hash = cryptoService.ComputeHash(fileStream);
        var hashString = Convert.ToBase64String(hash);
        return hashString.TrimEnd('=');
     }
  }
}


  WriteLine("MD5 Hash Code   : {0}", GetHashCode(FilePath, new MD5CryptoServiceProvider()));
  WriteLine("SHA1 Hash Code  : {0}", GetHashCode(FilePath, new SHA1CryptoServiceProvider()));
  WriteLine("SHA256 Hash Code: {0}", GetHashCode(FilePath, new SHA256CryptoServiceProvider()));
  WriteLine("SHA384 Hash Code: {0}", GetHashCode(FilePath, new SHA384CryptoServiceProvider()));
  WriteLine("SHA512 Hash Code: {0}", GetHashCode(FilePath, new SHA512CryptoServiceProvider()));

Answer 4

Here's the routine I'm currently using.

    using System.Security.Cryptography;

    public string HashFile(string filePath)
    {
        using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read))
        {
            return HashFile(fs);
        }
    }

    public string HashFile( FileStream stream )
    {
        StringBuilder sb = new StringBuilder();

        if( stream != null )
        {
            stream.Seek( 0, SeekOrigin.Begin );

            MD5 md5 = MD5CryptoServiceProvider.Create();
            byte[] hash = md5.ComputeHash( stream );
            foreach( byte b in hash )
                sb.Append( b.ToString( "x2" ) );

            stream.Seek( 0, SeekOrigin.Begin );
        }

        return sb.ToString();
    }