Craig Schwarze Craig Schwarze - 5 days ago 5
C# Question

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

Using C#, I want to create an MD5 hash of a text file. How can I accomplish this? Please include code. Many thanks!

Update: Thanks to everyone for their help. I've finally settled upon the following code -

// Create an MD5 hash digest of a file
public string MD5HashFile(string fn)
{
byte[] hash = MD5.Create().ComputeHash(File.ReadAllBytes(fn));
return BitConverter.ToString(hash).Replace("-", "");
}

Answer

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();
    }
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