/// <summary>
/// Unpacks a cipher formerly packed with <see cref="PackHeaderAndCypher(CryptoHeader, byte[])"/>.
/// </summary>
/// <param name="packedCipher">Packed cipher containing a header and its cipher.</param>
/// <param name="header">Receives the extracted header.</param>
/// <param name="cipher">Receives the extracted cipher.</param>
public static void UnpackHeaderAndCipher(byte[] packedCipher, out CryptoHeader header, out byte[] cipher)
{
if (packedCipher == null)
{
throw new ArgumentNullException("packedCipher");
}
int lastSeparatorPos = IndexOfLastSeparator(packedCipher, ExpectedSeparatorCount);
if (lastSeparatorPos < 0)
{
throw new CryptoExceptionInvalidCipherFormat();
}
// Read cipher part
int cipherLength = packedCipher.Length - lastSeparatorPos - 1;
cipher = new byte[cipherLength];
Array.Copy(packedCipher, lastSeparatorPos + 1, cipher, 0, cipherLength);
// Read header part
string headerString = Encoding.UTF8.GetString(packedCipher, 0, lastSeparatorPos + 1);
header = UnpackHeader(headerString);
}
/// <summary>
/// Pack an encryption header and its cipher together to a byte array.
/// </summary>
/// <param name="header">Header containing the encryption parameters.</param>
/// <param name="cipher">Cipher generated with those encryption parameters.</param>
/// <returns>Packed cipher.</returns>
public static byte[] PackHeaderAndCypher(CryptoHeader header, byte[] cipher)
{
if (header == null)
{
throw new ArgumentNullException("header");
}
if (cipher == null)
{
throw new ArgumentNullException("cipher");
}
StringBuilder sb = new StringBuilder();
sb.Append(header.AppName);
sb.Append(Separator);
sb.Append(header.AlgorithmName);
sb.Append(Separator);
sb.Append(CryptoUtils.BytesToBase64String(header.Nonce));
sb.Append(Separator);
sb.Append(header.KdfName);
sb.Append(Separator);
sb.Append(CryptoUtils.BytesToBase64String(header.Salt));
sb.Append(Separator);
sb.Append(header.Cost);
sb.Append(Separator);
string stringHeader = sb.ToString();
byte[] binaryHeader = CryptoUtils.StringToBytes(stringHeader);
byte[] result = new byte[cipher.Length + binaryHeader.Length];
Array.Copy(binaryHeader, 0, result, 0, binaryHeader.Length);
Array.Copy(cipher, 0, result, binaryHeader.Length, cipher.Length);
return(result);
}
/// <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>
/// Unpacks a cipher formerly packed with <see cref="PackHeaderAndCypher(CryptoHeader, byte[])"/>.
/// </summary>
/// <param name="packedCipher">Packed cipher containing a header and its cipher.</param>
/// <param name="expectedAppName">The app name which must match.</param>
/// <param name="header">Receives the extracted header.</param>
/// <param name="cipher">Receives the extracted cipher.</param>
/// <exception cref="CryptoExceptionInvalidCipherFormat">Thrown if it doesn't contain a valid header.</exception>
/// <exception cref="CryptoUnsupportedRevisionException">Thrown if it was packed with a future incompatible version.</exception>
public static void UnpackHeaderAndCipher(byte[] packedCipher, string expectedAppName, out CryptoHeader header, out byte[] cipher)
{
header = null;
cipher = null;
if (!HasMatchingHeader(packedCipher, expectedAppName, out int revision))
{
throw new CryptoExceptionInvalidCipherFormat();
}
if (revision > CryptoHeader.NewestSupportedRevision)
{
throw new CryptoUnsupportedRevisionException();
}
int expectedSeparatorCount = (revision > 1) ? 7 : 6;
int lastSeparatorPos = IndexOfLastSeparator(packedCipher, expectedSeparatorCount);
if (lastSeparatorPos < 0)
{
throw new CryptoExceptionInvalidCipherFormat();
}
// Read cipher part
int cipherLength = packedCipher.Length - lastSeparatorPos - 1;
cipher = new byte[cipherLength];
Array.Copy(packedCipher, lastSeparatorPos + 1, cipher, 0, cipherLength);
// Read header part
try
{
string headerString = Encoding.UTF8.GetString(packedCipher, 0, lastSeparatorPos + 1);
string[] parts = headerString.Split(new char[] { Separator });
header = new CryptoHeader
{
PackageName = expectedAppName,
Revision = revision,
AlgorithmName = parts[1],
Nonce = CryptoUtils.Base64StringToBytes(parts[2]),
KdfName = string.IsNullOrEmpty(parts[3]) ? null : parts[3],
Salt = string.IsNullOrEmpty(parts[4]) ? null : CryptoUtils.Base64StringToBytes(parts[4]),
Cost = string.IsNullOrEmpty(parts[5]) ? null : parts[5],
};
if (revision > 1)
{
header.Compression = parts[6];
}
}
catch (Exception)
{
throw new CryptoExceptionInvalidCipherFormat();
}
}
/// <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);
}
}
private static CryptoHeader UnpackHeader(string headerString)
{
string[] parts = headerString.Split(new char[] { Separator }, StringSplitOptions.RemoveEmptyEntries);
CryptoHeader result = new CryptoHeader();
result.AppName = parts[0];
result.AlgorithmName = parts[1];
result.Nonce = CryptoUtils.Base64StringToBytes(parts[2]);
result.KdfName = parts[3];
result.Salt = CryptoUtils.Base64StringToBytes(parts[4]);
result.Cost = parts[5];
return(result);
}
/// <inheritdoc/>
public byte[] Encrypt(
byte[] message,
byte[] key,
string encryptorName,
string compression = null)
{
if (message == null)
{
throw new ArgumentNullException(nameof(message));
}
if (key == null)
{
throw new ArgumentNullException(nameof(key));
}
if (_randomSource == null)
{
throw new ArgumentNullException(nameof(_randomSource));
}
if (string.IsNullOrWhiteSpace(encryptorName))
{
encryptorName = BouncyCastleXChaCha20.CryptoAlgorithmName;
}
ISymmetricEncryptionAlgorithm encryptor = new SymmetricEncryptionAlgorithmFactory().CreateAlgorithm(encryptorName);
// Prepare header
CryptoHeader header = new CryptoHeader();
header.PackageName = PackageName;
header.AlgorithmName = encryptor.Name;
header.Nonce = _randomSource.GetRandomBytes(encryptor.ExpectedNonceSize);
header.Compression = compression;
try
{
if (string.Equals(CompressionGzip, header.Compression, StringComparison.InvariantCultureIgnoreCase))
{
message = CompressUtils.Compress(message);
}
byte[] truncatedKey = CryptoUtils.TruncateKey(key, encryptor.ExpectedKeySize);
byte[] cipher = encryptor.Encrypt(message, truncatedKey, header.Nonce);
return(CryptoHeaderPacker.PackHeaderAndCypher(header, cipher));
}
catch (Exception ex)
{
throw new CryptoException("An unexpected error occured, while encrypting the message.", ex);
}
}