public static void Decrypt(byte[] input, byte[] output, BeaufortKey key)
{
Debug.Assert(input.Length == output.Length);
for (var i = 0; i < input.Length; i++)
{
if (input[i] == '\n' || input[i] == '\r')
{
output[i] = input[i];
continue;
}
var inputNormalized = input[i] - Constants.AsciiOffset;
var plain = (byte) inputNormalized + key.Current;
var outputNormalized =
(byte) (plain < Constants.AlphabetLength ? plain : (plain - Constants.AlphabetLength));
output[i] = (byte) (outputNormalized + Constants.AsciiOffset);
key.MoveNext();
}
}
void LoadDecryptedButton_Click(object sender, EventArgs e)
{
if (_fileDialog.ShowDialog() == DialogResult.OK)
{
var fInfo = new FileInfo(_fileDialog.FileName);
if (fInfo.Length > MaxFileSize)
{
// file too big to fit into the textbox, offer to encrypt to file directly
var message = "File too big to show in this window\nDo you want to encrypt directly to file?";
if (MessageBox.Show(message, "File too big", MessageBoxButtons.YesNo) != DialogResult.Yes)
{
return;
}
if (_saveDialog.ShowDialog() != DialogResult.OK)
{
return;
}
using (var writer = new StreamWriter(new BufferedStream(_saveDialog.OpenFile())))
using (var reader = new StreamReader(new BufferedStream(_fileDialog.OpenFile())))
{
var inBuffer = new char[Constants.BufferSize];
var outBuffer = new char[Constants.BufferSize];
var key = new BeaufortKey(Key);
int read;
while ((read = reader.Read(inBuffer, 0, Constants.BufferSize)) > 0)
{
BeaufortCipher.Encrypt(inBuffer, outBuffer, key);
writer.Write(outBuffer, 0, read);
}
}
}
else
{
using (var reader = new StreamReader(_fileDialog.OpenFile()))
{
DecryptedText = reader.ReadToEnd();
}
}
}
}
public static void Encrypt(char[] input, char[] output, BeaufortKey key)
{
Encoding.ASCII.GetBytes(input, 0, input.Length, DecryptedBuffer, 0);
Encrypt(DecryptedBuffer, EncryptedBuffer, key);
Encoding.ASCII.GetChars(EncryptedBuffer, 0, Constants.BufferSize, output, 0);
}