private void Decrypt_Click(object sender, EventArgs e)
{
if (textKey.TextLength == 0 || textFile.TextLength == 0)
{
MessageBox.Show("Please select file and input a key.");
}
else
{
tDes td = new tDes();
td.desKey = new byte[24];
td.desIV = new byte[8];
StringBuilder sb = new StringBuilder("", 32);
do
{
sb.Append(textKey.Text);
} while (sb.Length < 32);
Encoding.UTF8.GetBytes(sb.ToString(), 0, 24, td.desKey, 0);
Encoding.UTF8.GetBytes(sb.ToString(), 24, 8, td.desIV, 0);
td.inName = textFile.Text;
td.outName = textFile.Text + "_";
Thread th = new Thread(DecryptFile);
th.Start(td);
}
}
private static void DecryptFile(object param)
{
tDes td = (tDes)param;
//Create the file streams to handle the input and output files.
FileStream fin = new FileStream(td.inName, FileMode.Open, FileAccess.Read);
FileStream fout = new FileStream(td.outName, FileMode.OpenOrCreate, FileAccess.Write);
fout.SetLength(0);
//Create variables to help with read and write.
byte[] bin = new byte[100]; //This is intermediate storage for the encryption.
long rdlen = 0; //This is the total number of bytes written.
long totlen = fin.Length; //This is the total length of the input file.
int len; //This is the number of bytes to be written at a time.
try
{
TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
CryptoStream decStream = new CryptoStream(fout, tdes.CreateDecryptor(td.desKey, td.desIV), CryptoStreamMode.Write);
//Read from the input file, then encrypt and write to the output file.
while (rdlen < totlen)
{
len = fin.Read(bin, 0, 100);
decStream.Write(bin, 0, len);
rdlen = rdlen + len;
}
decStream.Close();
fout.Close();
fin.Close();
MessageBox.Show("finshed.");
}
catch (Exception e)
{
MessageBox.Show(e.Message);
fout.Close();
fin.Close();
Thread.CurrentThread.Abort();
}
}
