/// <summary>
/// Encrypts plaintext using the Encrypt-then-MAC (EtM) mode via the Rijndael cipher in
/// CBC mode with a password derived HMAC SHA-512 salt.
/// </summary>
/// <param name="plaintext">The plaintext to encrypt.</param>
/// <param name="password">The password to encrypt the plaintext with.</param>
/// <param name="iv">The initialization vector. Must be 128-bits.</param>
/// <param name="keySize">The cipher key size. 256-bit is stronger, but slower.</param>
/// <returns>The EtM ciphertext.</returns>
public static new byte[] Encrypt(byte[] plaintext, string password, byte[] iv, KeySize keySize)
{
// Generate AE keys
var keyRing = AeKeyRing.Generate(password);
// Encrypt the plaintext
var ciphertext = Rijndael.Encrypt(plaintext, keyRing.CipherKey, iv, keySize);
// Calculate the MAC from the ciphertext
var mac = CalculateMac(ciphertext, keyRing.MacKey);
// Append the MAC to the ciphertext
var etmCiphertext = new byte[ciphertext.Length + mac.Length];
Buffer.BlockCopy(ciphertext, 0, etmCiphertext, 0, ciphertext.Length);
Buffer.BlockCopy(mac, 0, etmCiphertext, ciphertext.Length, mac.Length);
// IV + Cipher + MAC
return(etmCiphertext);
}
private void btnEncrypt_Click(object sender, EventArgs e)
{
string ToEncrypt;
try { ToEncrypt = FilePath + lbFiles.SelectedItem.ToString(); }
catch (Exception) { MessageBox.Show("You must select an item to encrypt or decrypt!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); return; }
if (string.IsNullOrWhiteSpace(txtPassword.Text))
{
MessageBox.Show("You must enter a password to decrypt or encrypt files!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); return;
}
string Password = txtPassword.Text;
string Output = FilePath + lbFiles.SelectedItem.ToString() + ".locked";
if (Path.GetExtension(ToEncrypt).ToLower() == ".locked")
{
MessageBox.Show("File is already encrypted!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); return;
}
else
{
}
Rijndael.Encrypt(ToEncrypt, Output, txtPassword.Text, KS);
File.Delete(ToEncrypt);
WriteToConsole("Encrypted file successfully");
}