public static async Task <string> Decrypt(string cipherText, string password, string salt = "Kosher",
string hashAlgorithm = "SHA1",
int passwordIterations = 2,
int keySize = 256)
{
return(await Task.Run(() =>
{
if (string.IsNullOrEmpty(cipherText))
{
return null;
}
if (string.IsNullOrEmpty(password))
{
return null;
}
byte[] initialVectorBytes;
byte[] saltValueBytes;
byte[] cipherTextBytes = Convert.FromBase64String(cipherText);
// Extract metadata from file
AESMetadata metadata = new AESMetadata();
if (!metadata.GetMetadata(cipherTextBytes))
{
// Metadata parsing error
DialogResult result = MessageBox.Show("Unable to parse file metadata.\nAttempt to open anyway?\n(May result in a \'Incorrect Key\' error if the salt is wrong.)",
"Missing or Corrupted Metadata", MessageBoxButtons.YesNoCancel, MessageBoxIcon.Asterisk, MessageBoxDefaultButton.Button1, MessageBoxOptions.DefaultDesktopOnly);
if (result == DialogResult.Yes)
{
// Default initialization vector from builds v1.1.2 and older
const string default_IV = "16CHARSLONG12345";
initialVectorBytes = Encoding.ASCII.GetBytes(default_IV);
saltValueBytes = Encoding.ASCII.GetBytes(salt);
}
else
{
PublicVar.metadataCorrupt = true;
return null;
}
}
else
{
saltValueBytes = metadata.Salt;
initialVectorBytes = metadata.InitialVector;
metadata.DeleteMetadataFromBuffer(ref cipherTextBytes);
}
PasswordDeriveBytes derivedPassword = new PasswordDeriveBytes
(password, saltValueBytes, hashAlgorithm, passwordIterations);
byte[] keyBytes = derivedPassword.GetBytes(keySize / 8);
RijndaelManaged symmetricKey = new RijndaelManaged();
symmetricKey.Mode = CipherMode.CBC;
byte[] plainTextBytes = new byte[cipherTextBytes.Length];
int byteCount = 0;
using (MemoryStream memStream = new MemoryStream(cipherTextBytes))
{
using (ICryptoTransform decryptor = symmetricKey.CreateDecryptor
(keyBytes, initialVectorBytes))
{
using (CryptoStream cryptoStream
= new CryptoStream(memStream, decryptor, CryptoStreamMode.Read))
{
byteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
memStream.Close();
cryptoStream.Close();
}
}
symmetricKey.Dispose();
}
derivedPassword.Dispose();
return Encoding.UTF8.GetString(plainTextBytes, 0, byteCount);
}));
}
public static async Task <string> Encrypt(string plainText, string password,
string salt = null, string hashAlgorithm = "SHA1",
int passwordIterations = 2, int keySize = 256)
{
return(await Task.Run(() =>
{
if (string.IsNullOrEmpty(plainText))
{
return null;
}
if (string.IsNullOrEmpty(password))
{
return null;
}
byte[] plainTextBytes;
byte[] saltValueBytes;
// In case user wants a random salt or salt is null/empty for some other reason
if (string.IsNullOrEmpty(salt))
{
saltValueBytes = new byte[64]; // Nice and long
saltValueBytes = GenerateSecureNonZeroByteArray(saltValueBytes.Length);
}
else
{
saltValueBytes = Encoding.ASCII.GetBytes(salt);
}
plainTextBytes = Encoding.UTF8.GetBytes(plainText);
PasswordDeriveBytes derivedPassword = new PasswordDeriveBytes
(password, saltValueBytes, hashAlgorithm, passwordIterations);
// Null password; adds *some* memory dump protection
password = null;
byte[] keyBytes = derivedPassword.GetBytes(keySize / 8);
RijndaelManaged symmetricKey = new RijndaelManaged();
symmetricKey.Mode = CipherMode.CBC;
// Generate IV
symmetricKey.IV = GenerateSecureNonZeroByteArray(symmetricKey.IV.Length);
byte[] cipherTextBytes = null;
using (MemoryStream memStream = new MemoryStream())
{
AESMetadata.WriteMetadata(memStream, symmetricKey.IV, saltValueBytes);
using (ICryptoTransform encryptor = symmetricKey.CreateEncryptor
(keyBytes, symmetricKey.IV))
{
using (CryptoStream cryptoStream = new CryptoStream
(memStream, encryptor, CryptoStreamMode.Write))
{
cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
cryptoStream.FlushFinalBlock();
cipherTextBytes = memStream.ToArray();
memStream.Close();
cryptoStream.Close();
}
}
}
symmetricKey.Dispose();
derivedPassword.Dispose();
return Convert.ToBase64String(cipherTextBytes);
}));
}
