/// <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);
}
}
/// <inheritdoc/>
public byte[] Decrypt(byte[] packedCipher, byte[] key)
{
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);
try
{
byte[] truncatedKey = CryptoUtils.TruncateKey(key, decryptor.ExpectedKeySize);
byte[] message = decryptor.Decrypt(cipher, truncatedKey, 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);
}
}