private void Decrypt_Click(object sender, EventArgs e)
{
decryptMessageLabel.Show();
this.decryptMessageLabel.ForeColor = Color.Orange;
this.decryptMessageLabel.Text = "Decryption in progress";
if (outputFilenameTB.Text.Equals(string.Empty))
{
this.decryptMessageLabel.ForeColor = Color.Red;
this.decryptMessageLabel.Text = "Decryption failed";
progressBar.Hide();
MessageBox.Show("No output filename was chosen");
return;
}
if (fileTB.Text.Equals(string.Empty))
{
this.decryptMessageLabel.ForeColor = Color.Red;
this.decryptMessageLabel.Text = "Decryption failed";
progressBar.Hide();
MessageBox.Show("No input file was chosen");
return;
}
if (approvedUsersCB.Text.Equals(string.Empty))
{
this.decryptMessageLabel.ForeColor = Color.Red;
this.decryptMessageLabel.Text = "Decryption failed";
progressBar.Hide();
MessageBox.Show("No user was chosen");
return;
}
if (userPassTB.Text.Equals(string.Empty))
{
this.decryptMessageLabel.ForeColor = Color.Red;
this.decryptMessageLabel.Text = "Decryption failed";
progressBar.Hide();
MessageBox.Show("Incorrect password");
return;
}
var encryptedFileContent = File.ReadAllText(fileTB.Text);
var XMLStringMetadata = encryptedFileContent.Split(new[] { "</EncryptedFileHeader>" }, StringSplitOptions.None)[0] + "</EncryptedFileHeader>";
var encyptedData = encryptedFileContent.Split(new[] { "</EncryptedFileHeader>" }, StringSplitOptions.None)[1];
var doc = new XmlDocument();
doc.LoadXml(XMLStringMetadata);
XmlNodeList approvedUserNodes = doc.SelectNodes("/EncryptedFileHeader/ApprovedUsers/User");
var decryptionMode = doc.SelectSingleNode("/EncryptedFileHeader/CipherMode").InnerText;
var fileIV = doc.SelectSingleNode("/EncryptedFileHeader/IV").InnerText;
CipherMode mode = 0;
var cipherMode = decryptionMode;
if (cipherMode == "ECB")
{
mode = CipherMode.ECB;
}
else if (cipherMode == "CBC")
{
mode = CipherMode.CBC;
}
else if (cipherMode == "CFB")
{
mode = CipherMode.CFB;
}
this.decryptMessageLabel.ForeColor = Color.Red;
this.decryptMessageLabel.Text = "Decryption failed"; //this message is needed, when the user choose receiver that is not in the header of the file
foreach (XmlNode node in approvedUserNodes)
{
if (approvedUsersCB.Text == node.SelectSingleNode("Email").InnerText)
{
progressBar.Show();
if (backgroundWorker1.IsBusy != true)
{
// Start the asynchronous operation.
backgroundWorker1.RunWorkerAsync();
}
var encryptedSessionKey = node.SelectSingleNode("SessionKey").InnerText;
string encryptedPrivKey, userIV;
using (StreamReader sr = new StreamReader(@"..\..\users\privateKeys\" + approvedUsersCB.Text + ".txt"))
{
encryptedPrivKey = sr.ReadToEnd();
}
using (StreamReader sr = new StreamReader(@"..\..\users\vectorsIV\" + approvedUsersCB.Text + ".txt"))
{
userIV = sr.ReadToEnd();
}
var serviceAESDecr = new ServiceAES(CipherMode.ECB, userPassTB.Text, true);
var privKey = serviceAESDecr.Decrypt(encryptedPrivKey, Convert.FromBase64String(userIV));
var serviceRSADecr = new ServiceRSA(privKey, true);
var sessionKey = serviceRSADecr.DecryptSessionKey(encryptedSessionKey);
var extensionOfFile = Path.GetExtension(doc.SelectSingleNode("/EncryptedFileHeader/Extension").InnerText);
var dirToSave = fileTB.Text.Substring(0, fileTB.Text.LastIndexOf("\\") + 1);
var outputFileName = dirToSave + outputFilenameTB.Text + extensionOfFile;
File.WriteAllText(Path.GetFullPath(outputFileName), // START DECRYPTING
ServiceRijndaelAES.DecryptStringFromBytes(
Convert.FromBase64String(encyptedData),
Convert.FromBase64String(sessionKey),
Convert.FromBase64String(fileIV), mode));
this.decryptMessageLabel.ForeColor = Color.Green;
this.decryptMessageLabel.Text = "Decryption suceeded";
}
}
}
private void Encrypt_Click(object sender, EventArgs e)
{
encryptMessageLabel.Show();
this.encryptMessageLabel.ForeColor = Color.Orange;
this.encryptMessageLabel.Text = "Encryption in progress";
if (encryptionModeCB.SelectedItem == null)
{
this.encryptMessageLabel.ForeColor = Color.Red;
this.encryptMessageLabel.Text = "Encryption failed";
encryptPB.Hide();
MessageBox.Show("No encryption mode was chosen");
return;
}
if (outputFilenameTB.Text.Equals(string.Empty))
{
this.encryptMessageLabel.ForeColor = Color.Red;
this.encryptMessageLabel.Text = "Encryption failed";
encryptPB.Hide();
MessageBox.Show("No output filename was chosen");
return;
}
if (fileTB.Text.Equals(string.Empty))
{
this.encryptMessageLabel.ForeColor = Color.Red;
this.encryptMessageLabel.Text = "Encryption failed";
encryptPB.Hide();
MessageBox.Show("No input file was chosen");
return;
}
if (approvedUsersLB.CheckedItems.Count <= 0)
{
this.encryptMessageLabel.ForeColor = Color.Red;
this.encryptMessageLabel.Text = "Encryption failed";
encryptPB.Hide();
MessageBox.Show("No receiver/receivers was/were chosen");
return;
}
var users = new List <User>();
byte[] fileIV;
using (RijndaelManaged rijAlg = new RijndaelManaged())
{
rijAlg.GenerateIV();
fileIV = rijAlg.IV;
}
var keySize = 192;
var blockSize = 128;
var sessionKey = GetSessionKey(keySize / 8); // length of key must be keySize/8
foreach (var username in approvedUsersLB.CheckedItems)
{
string pubKey, privKey;
using (StreamReader sr = new StreamReader(@"..\..\users\publicKeys\" + username + ".txt"))
{
pubKey = sr.ReadToEnd();
}
using (StreamReader sr = new StreamReader(@"..\..\users\privateKeys\" + username + ".txt"))
{
privKey = sr.ReadToEnd();
}
var serviceRSA = new ServiceRSA(pubKey);
var encryptedSessionKey = serviceRSA.EncryptSessionKey(sessionKey); // Encrypting session key of the user by public key of the same user
users.Add(new User(username.ToString(), encryptedSessionKey));
}
CipherMode mode = 0;
var cipherMode = encryptionModeCB.SelectedItem.ToString();
if (cipherMode == "ECB")
{
mode = CipherMode.ECB;
}
else if (cipherMode == "CBC")
{
mode = CipherMode.CBC;
}
else if (cipherMode == "OFB")
{
this.encryptMessageLabel.ForeColor = Color.Red;
this.encryptMessageLabel.Text = "Encryption failed";
MessageBox.Show("OFB isnt supported in .NET");
encryptPB.Hide();
return;
}
else if (cipherMode == "CFB")
{
mode = CipherMode.CFB;
}
var headers = new XElement("EncryptedFileHeader");
headers.Add(new XElement("Algorithm", "AES"));
headers.Add(new XElement("KeySize", keySize));
headers.Add(new XElement("BlockSize", blockSize));
headers.Add(new XElement("CipherMode", cipherMode));
headers.Add(new XElement("IV", Convert.ToBase64String(fileIV)));
var extensionOfFile = Path.GetExtension(fileTB.Text);
headers.Add(new XElement("Extension", extensionOfFile));
var approvedUsers = new XElement("ApprovedUsers");
foreach (var user in users)
{
approvedUsers.Add(new XElement("User",
new XElement("Email", user.name),
new XElement("SessionKey", user.encryptedSessionKey)));
}
headers.Add(new XElement(approvedUsers));
var xmlFile = new XDocument(headers);
var dirToSave = fileTB.Text.Substring(0, fileTB.Text.LastIndexOf("\\") + 1);
var outputFileName = dirToSave + outputFilenameTB.Text;
xmlFile.Save(outputFileName);
encryptPB.Show();
if (backgroundWorker1.IsBusy != true)
{
// Start the asynchronous operation.
backgroundWorker1.RunWorkerAsync();
}
using (var swEncrypt = File.AppendText(outputFileName))
{
//Write all data to the stream.
var sessionKeyInBytes = Encoding.ASCII.GetBytes(sessionKey);
swEncrypt.Write(
Convert.ToBase64String(
ServiceRijndaelAES.EncryptStringToBytes(this,
File.ReadAllText(
fileTB.Text), sessionKeyInBytes, mode, fileIV)));
}
this.encryptMessageLabel.ForeColor = Color.Green;
this.encryptMessageLabel.Text = "Encryption suceeded";
}
