Possible to calculate MD5 (or other) hash with buffered reads?

Question

I need to calculate checksums of quite large files (gigabytes). This can be accomplished using the following method:

    private byte[] calcHash(string file         


        

Answer 1

I like the answer above but for the sake of completeness, and being a more general solution, refer to the CryptoStream class. If you are already handling streams, it is easy to wrap your stream in a CryptoStream, passing a HashAlgorithm as the ICryptoTransform parameter.

var file = new FileStream("foo.txt", FileMode.Open, FileAccess.Write);
var md5 = MD5.Create();
var cs = new CryptoStream(file, md5, CryptoStreamMode.Write);
while (notDoneYet)
{
    buffer = Get32MB();
    cs.Write(buffer, 0, buffer.Length);
}
System.Console.WriteLine(BitConverter.ToString(md5.Hash));

You might have to close the stream before getting the hash (so the HashAlgorithm knows it's done).