/// <summary>
/// Gets the OpenPGP encoded representation of the ESK Sequence.
/// </summary>
/// <returns>Returns a byte array that represents the encoded
/// ESKSequence.</returns>
/// <remarks>No remarks</remarks>
public override byte[] GetEncoded()
{
byte[] bOutput = new byte[0];
if (!bUpdated)
{
//nothing was updated, we can reconstruct the message
//in the exact same order
IEnumerator ieKeys = alAllKeys.GetEnumerator();
while (ieKeys.MoveNext())
{
Packet pKey = (Packet)ieKeys.Current;
byte[] bKey = pKey.Generate();
byte[] bOldOutput = new byte[bOutput.Length];
bOutput.CopyTo(bOldOutput, 0);
bOutput = new byte[bOldOutput.Length + bKey.Length];
bOldOutput.CopyTo(bOutput, 0);
bKey.CopyTo(bOutput, bOldOutput.Length);
}
}
else
{
// At first we will produce the Symmetrically encrypted
// session key packets
IEnumerator ieSymKeys = alSymKeys.GetEnumerator();
while (ieSymKeys.MoveNext())
{
SymSessionKeyPacket sskpKey = (SymSessionKeyPacket)ieSymKeys.Current;
byte[] bKey = sskpKey.Generate();
byte[] bOldOutput = new byte[bOutput.Length];
bOutput.CopyTo(bOldOutput, 0);
bOutput = new byte[bOldOutput.Length + bKey.Length];
bOldOutput.CopyTo(bOutput, 0);
bKey.CopyTo(bOutput, bOldOutput.Length);
}
// Now come the Public Key encrypted session key packets
IEnumerator ieAsymKeys = alAsymKeys.GetEnumerator();
while (ieAsymKeys.MoveNext())
{
AsymSessionKeyPacket askpKey = (AsymSessionKeyPacket)ieAsymKeys.Current;
byte[] bKey = askpKey.Generate();
byte[] bOldOutput = new byte[bOutput.Length];
bOutput.CopyTo(bOldOutput, 0);
bOutput = new byte[bOldOutput.Length + bKey.Length];
bOldOutput.CopyTo(bOutput, 0);
bKey.CopyTo(bOutput, bOldOutput.Length);
}
}
return(bOutput);
}
/// <summary>
/// Decrypts the encrypted message if it is a symmetrically encrypted
/// message with the passphrase given as argument.
/// </summary>
/// <param name="strPassphrase">The passphrase that was used to encrypt
/// the message</param>
/// <returns>Returns the message that was encrypted. Usually this is
/// an compressed or literal message.</returns>
/// <remarks>No remarks</remarks>
public Message Decrypt(string strPassphrase)
{
if (esKeys.SymKeys.Count == 0)
{
throw new Exception("This message is not symmetrically encrypted. Please provide a keyring rather than a passphrase!");
}
Packet[] pContent = new Packet[0];
Packet[] pReturn = new Packet[0];
IEnumerator ieKeys = esKeys.SymKeys.GetEnumerator();
while (ieKeys.MoveNext())
{
SymSessionKeyPacket skpKey = (SymSessionKeyPacket)ieKeys.Current;
byte[] key = skpKey.S2KSpecifier.GetKey(strPassphrase, CipherHelper.CipherKeySize(skpKey.Algorithm));
try {
SymmetricAlgorithm saAlgo = CipherHelper.CreateSymAlgorithm(skpKey.Algorithm);
pContent = sepData.Decrypt(key, saAlgo);
} catch (System.Security.Cryptography.CryptographicException) {}
if (pContent.Length > 0)
{
pReturn = pContent;
}
}
if (pReturn.Length == 0)
{
throw new System.Security.Cryptography.CryptographicException("Wrong passphrase!");
}
// now we need to look what kind of message was hidden in the
// encrypted data
// it can be either a literal message
LiteralMessage lmLiteral = new LiteralMessage();
try {
int iPos = lmLiteral.ParseMessage(pReturn);
return(lmLiteral);
} catch (Exception) {}
// or an compressed Message
CompressedMessage cmCompressed = new CompressedMessage();
try {
int iPos = cmCompressed.ParseMessage(pReturn);
return(cmCompressed);
} catch (Exception) {}
throw new System.ArgumentException("Encrypted package content is not a valid message!");
}
/// <summary>
/// Adds an symmetrically encrypted session key to the ESK
/// Sequence.
/// </summary>
/// <param name="sskpKey">A symmetrical Session key packet that
/// is to be added the the ESKSequence.</param>
/// <remarks>No remarks</remarks>
public void AddSymSessionKey(SymSessionKeyPacket sskpKey)
{
bUpdated = true;
alSymKeys.Add(sskpKey);
}
/// <summary>
/// Adds an symmetrically encrypted session key to the ESK
/// Sequence.
/// </summary>
/// <param name="sskpKey">A symmetrical Session key packet that
/// is to be added the the ESKSequence.</param>
/// <remarks>No remarks</remarks>
public void AddSymSessionKey(SymSessionKeyPacket sskpKey)
{
bUpdated = true;
alSymKeys.Add(sskpKey);
}