/// <inheritdoc/>
public byte[] Decrypt(byte[] packedCipher, SecureString password)
{
if (packedCipher == null)
{
throw new ArgumentNullException("packedCipher");
}
CryptoHeader header;
byte[] cipher;
CryptoHeaderPacker.UnpackHeaderAndCipher(packedCipher, PackageName, out header, out cipher);
ISymmetricEncryptionAlgorithm decryptor = new SymmetricEncryptionAlgorithmFactory().CreateAlgorithm(header.AlgorithmName);
IKeyDerivationFunction kdf = new KeyDerivationFactory().CreateKdf(header.KdfName);
try
{
int cost = int.Parse(header.Cost);
byte[] key = kdf.DeriveKeyFromPassword(password, decryptor.ExpectedKeySize, header.Salt, cost);
byte[] message = decryptor.Decrypt(cipher, key, header.Nonce);
if (string.Equals(CompressionGzip, header.Compression, StringComparison.InvariantCultureIgnoreCase))
{
message = CompressUtils.Decompress(message);
}
return(message);
}
catch (Exception ex)
{
throw new CryptoDecryptionException("Could not decrypt cipher, probably because the key is wrong.", ex);
}
}
/// <summary>
/// Decrypts a cipher, which was encrypted with <see cref="Encrypt(byte[],string,KeyDerivationCostType,ICryptoRandomSource,string,string)"/>.
/// </summary>
/// <param name="packedCipher">The cipher containing a header with the
/// necessary parameters for decryption.</param>
/// <param name="password">The password which was used for encryption.</param>
/// <returns>The plain text message.</returns>
public byte[] Decrypt(byte[] packedCipher, string password)
{
if (packedCipher == null)
{
throw new ArgumentNullException("packedCipher");
}
CryptoHeader header;
byte[] cipher;
CryptoHeaderPacker.UnpackHeaderAndCipher(packedCipher, out header, out cipher);
if (_appName != header.AppName)
{
throw new CryptoExceptionInvalidCipherFormat();
}
ISymmetricEncryptionAlgorithm decryptor = new SymmetricEncryptionAlgorithmFactory().CreateAlgorithm(header.AlgorithmName);
IKeyDerivationFunction kdf = new KeyDerivationFactory().CreateKdf(header.KdfName);
try
{
int cost = int.Parse(header.Cost);
byte[] key = kdf.DeriveKeyFromPassword(password, decryptor.ExpectedKeySize, header.Salt, cost);
byte[] message = decryptor.Decrypt(cipher, key, header.Nonce);
return(message);
}
catch (Exception ex)
{
throw new CryptoDecryptionException("Could not decrypt cipher, probably because the key is wrong.", ex);
}
}
/// <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);
}
}
