Appending byte and stream

Question

I want to append byte array to stream i opened but just to pass it to hash algorithm and compute the hash, something like:

byte[] data;

using (BufferedStream bs = new BufferedStream(File.OpenRead(path), 1200000))
{
    MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();

    byte[] hash = md5.ComputeHash(data + bs);
}

I don't know how to do "data + bs" or "bs + data" part... Any idea about this?

Answer 1

Why wouldn't you simply do something like this:

public static byte[] MD5Hash( byte[] salt, Stream s , int blockSize )
{
  MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider() ;

  md5.Initialize();

  md5.TransformBlock(salt,0,salt.Length,salt,0) ;

  byte[] buf  = new byte[blockSize];
  int    bufl ;
  while ( (bufl=s.Read( buf , 0 , buf.Length )) > 0 )
  {
    md5.TransformBlock(buf,0,bufl,buf,0) ;
  }
  md5.TransformFinalBlock(buf,0,0) ;

  return md5.Hash ;
}

Answer 2

Do this:

byte[] hash = md5.ComputeHash(data + ReadToEnd(bs));

And, your ReadToEnd function:

public static byte[] ReadToEnd(Stream input)
{
    byte[] buffer = new byte[16*1024];
    using (MemoryStream ms = new MemoryStream())
    {
        int read;
        while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
        {
            ms.Write(buffer, 0, read);
        }
        return ms.ToArray();
    }
}

Answer 3

// here is a quick approach to your original question:
List<byte> raw = new List<byte>(data);
raw.AddRange(File.ReadAllBytes("filePath.ext"));

To do this without using List (in other words arrays), use Array.Copy(...) to copy the first and second arrays into a new array of a larger size. (Personally, I prefer Lists in C#, Vectors in C++) If you have 1200000 bytes max and don't want to pull everything from the file, then you could use this code to your advantage: Best way to read a large file into a byte array in C#? where numBytes is the number of bytes you want to read in.