Creating hash for folder

Question

i need to create hash for folder, that contains some files. I already done this task for each of files, but i searching the way to create one hash for all files in folder.

Answer 1

Dunc's answer works well; however, it does not handle an empty directory. The code below returns the MD5 'd41d8cd98f00b204e9800998ecf8427e' (the MD5 for a 0 length character stream) for an empty directory.

public static string CreateDirectoryMd5(string srcPath)
{
    var filePaths = Directory.GetFiles(srcPath, "*", SearchOption.AllDirectories).OrderBy(p => p).ToArray();

    using (var md5 = MD5.Create())
    {
        foreach (var filePath in filePaths)
        {
            // hash path
            byte[] pathBytes = Encoding.UTF8.GetBytes(filePath);
            md5.TransformBlock(pathBytes, 0, pathBytes.Length, pathBytes, 0);

            // hash contents
            byte[] contentBytes = File.ReadAllBytes(filePath);

            md5.TransformBlock(contentBytes, 0, contentBytes.Length, contentBytes, 0);
        }

        //Handles empty filePaths case
        md5.TransformFinalBlock(new byte[0], 0, 0);

        return BitConverter.ToString(md5.Hash).Replace("-", "").ToLower();
    }
}