/// <inheritdoc/>
public byte[] Encrypt(
byte[] message,
SecureString password,
KeyDerivationCostType costType,
string encryptorName,
string kdfName = Pbkdf2.CryptoKdfName,
string compression = null)
{
if (message == null)
{
throw new ArgumentNullException(nameof(message));
}
ValidatePassword(password);
if (_randomSource == null)
{
throw new ArgumentNullException(nameof(_randomSource));
}
if (string.IsNullOrWhiteSpace(encryptorName))
{
encryptorName = BouncyCastleXChaCha20.CryptoAlgorithmName;
}
if (string.IsNullOrWhiteSpace(kdfName))
{
encryptorName = Pbkdf2.CryptoKdfName;
}
ISymmetricEncryptionAlgorithm encryptor = new SymmetricEncryptionAlgorithmFactory().CreateAlgorithm(encryptorName);
IKeyDerivationFunction kdf = new KeyDerivationFactory().CreateKdf(kdfName);
// Prepare header
CryptoHeader header = new CryptoHeader();
header.PackageName = PackageName;
header.AlgorithmName = encryptor.Name;
header.Nonce = _randomSource.GetRandomBytes(encryptor.ExpectedNonceSize);
header.KdfName = kdf.Name;
header.Salt = _randomSource.GetRandomBytes(kdf.ExpectedSaltSizeBytes);
int cost = kdf.RecommendedCost(costType);
header.Cost = cost.ToString();
header.Compression = compression;
try
{
if (string.Equals(CompressionGzip, header.Compression, StringComparison.InvariantCultureIgnoreCase))
{
message = CompressUtils.Compress(message);
}
byte[] key = kdf.DeriveKeyFromPassword(password, encryptor.ExpectedKeySize, header.Salt, cost);
byte[] cipher = encryptor.Encrypt(message, key, header.Nonce);
return(CryptoHeaderPacker.PackHeaderAndCypher(header, cipher));
}
catch (Exception ex)
{
throw new CryptoException("An unexpected error occured, while encrypting the message.", ex);
}
}
/// <summary>
/// Encrypts a message with a user password, and adds a header containing all information
/// necessary for the decryption (algorithm, nonce, salt, ...).
/// </summary>
/// <param name="message">Plain text message to encrypt.</param>
/// <param name="password">Password to use for encryption, minimum length is 7 characters.</param>
/// <param name="costType">The cost type to use for encryption.</param>
/// <param name="randomSource">A cryptographically safe random source.</param>
/// <param name="encryptorName">The name of an encryption algorithm which shall be used to
/// do the encryption.</param>
/// <param name="kdfName">The name of a key derivation function, which can convert the
/// password to a key.</param>
/// <returns>A binary array containing the cipher.</returns>
public byte[] Encrypt(
byte[] message,
string password,
KeyDerivationCostType costType,
ICryptoRandomSource randomSource,
string encryptorName,
string kdfName = Pbkdf2.CryptoKdfName)
{
if (message == null)
{
throw new ArgumentNullException("message");
}
ValidatePassword(password);
if (randomSource == null)
{
throw new ArgumentNullException("randomSource");
}
if (string.IsNullOrWhiteSpace(encryptorName))
{
encryptorName = BouncyCastleAesGcm.CryptoAlgorithmName;
}
if (string.IsNullOrWhiteSpace(kdfName))
{
encryptorName = Pbkdf2.CryptoKdfName;
}
ISymmetricEncryptionAlgorithm encryptor = new SymmetricEncryptionAlgorithmFactory().CreateAlgorithm(encryptorName);
IKeyDerivationFunction kdf = new KeyDerivationFactory().CreateKdf(kdfName);
// Prepare header
CryptoHeader header = new CryptoHeader();
header.AppName = _appName;
header.AlgorithmName = encryptor.Name;
header.Nonce = randomSource.GetRandomBytes(encryptor.ExpectedNonceSize);
header.KdfName = kdf.Name;
header.Salt = randomSource.GetRandomBytes(kdf.ExpectedSaltSizeBytes);
int cost = kdf.RecommendedCost(costType);
header.Cost = cost.ToString();
try
{
byte[] key = kdf.DeriveKeyFromPassword(password, encryptor.ExpectedKeySize, header.Salt, cost);
byte[] cipher = encryptor.Encrypt(message, key, header.Nonce);
return(CryptoHeaderPacker.PackHeaderAndCypher(header, cipher));
}
catch (Exception ex)
{
throw new CryptoException("An unexpected error occured, while encrypting the message.", ex);
}
}
/// <inheritdoc />
public int RecommendedCost(KeyDerivationCostType costType)
{
switch (costType)
{
case KeyDerivationCostType.Low:
return(1000);
case KeyDerivationCostType.High:
return(10000); // measured 225ms (targeting ⅕s) on a mid-range mobile device in 2021
default:
throw new ArgumentOutOfRangeException("costType");
}
}
/// <inheritdoc />
public int RecommendedCost(KeyDerivationCostType costType)
{
switch (costType)
{
case KeyDerivationCostType.Low:
return(1000);
case KeyDerivationCostType.High:
return(10000);
default:
throw new ArgumentOutOfRangeException("costType");
}
}
