Question

Need MD5 hash for an in memory System.Drawing.Image

Answer 1

Here is a basic snippet. See also @JaredReisinger ‘s comment for some questions.

using System.Security.Cryptography;
using System.Text;
using System.Drawing.Imaging;
// ...

// get the bytes from the image
byte[] bytes = null;
using( MemoryStream ms = new MemoryStream() )
{
    image.Save(ms,ImageFormat.Gif); // gif for example
    bytes =  ms.ToArray();
}

// hash the bytes
MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
byte[] hash = md5.ComputeHash(bytes);

// make a hex string of the hash for display or whatever
StringBuilder sb = new StringBuilder();
foreach (byte b in hash)
{
   sb.Append(b.ToString("x2").ToLower());
}