/// <summary>
/// Computes the MD5 checksum of the content.
/// </summary>
/// <remarks>
/// Computes the MD5 checksum of the MIME content in its canonical
/// format and then base64-encodes the result.
/// </remarks>
/// <returns>The md5sum of the content.</returns>
/// <exception cref="System.InvalidOperationException">
/// The <see cref="ContentObject"/> is <c>null</c>.
/// </exception>
public string ComputeContentMd5 ()
{
if (ContentObject == null)
throw new InvalidOperationException ("Cannot compute Md5 checksum without a ContentObject.");
using (var stream = ContentObject.Open ()) {
byte[] checksum;
using (var filtered = new FilteredStream (stream)) {
if (ContentType.Matches ("text", "*"))
filtered.Add (new Unix2DosFilter ());
using (var md5 = MD5.Create ())
checksum = md5.ComputeHash (filtered);
}
var base64 = new Base64Encoder (true);
var digest = new byte[base64.EstimateOutputLength (checksum.Length)];
int n = base64.Flush (checksum, 0, checksum.Length, digest);
return Encoding.ASCII.GetString (digest, 0, n);
}
}
