/**
* Decrypt a message.
*
* @param ciphertext The {@link WhisperMessage} to decrypt.
* @param callback A callback that is triggered after decryption is complete,
* but before the updated session state has been committed to the session
* DB. This allows some implementations to store the committed plaintext
* to a DB first, in case they are concerned with a crash happening between
* the time the session state is updated but before they're able to store
* the plaintext to disk.
*
* @return The plaintext.
* @throws InvalidMessageException if the input is not valid ciphertext.
* @throws DuplicateMessageException if the input is a message that has already been received.
* @throws LegacyMessageException if the input is a message formatted by a protocol version that
* is no longer supported.
* @throws NoSessionException if there is no established session for this contact.
*/
public byte[] Decrypt(WhisperMessage ciphertext, DecryptionCallback callback)
{
lock (SESSION_LOCK)
{
if (!sessionStore.ContainsSession(remoteAddress))
{
throw new NoSessionException($"No session for: {remoteAddress}");
}
SessionRecord sessionRecord = sessionStore.LoadSession(remoteAddress);
byte[] plaintext = Decrypt(sessionRecord, ciphertext);
callback.HandlePlaintext(plaintext);
sessionStore.StoreSession(remoteAddress, sessionRecord);
return(plaintext);
}
}
/**
* Decrypt a message.
*
* @param ciphertext The {@link PreKeyWhisperMessage} to decrypt.
* @param callback A callback that is triggered after decryption is complete,
* but before the updated session state has been committed to the session
* DB. This allows some implementations to store the committed plaintext
* to a DB first, in case they are concerned with a crash happening between
* the time the session state is updated but before they're able to store
* the plaintext to disk.
*
* @return The plaintext.
* @throws InvalidMessageException if the input is not valid ciphertext.
* @throws DuplicateMessageException if the input is a message that has already been received.
* @throws LegacyMessageException if the input is a message formatted by a protocol version that
* is no longer supported.
* @throws InvalidKeyIdException when there is no local {@link org.whispersystems.libaxolotl.state.PreKeyRecord}
* that corresponds to the PreKey ID in the message.
* @throws InvalidKeyException when the message is formatted incorrectly.
* @throws UntrustedIdentityException when the {@link IdentityKey} of the sender is untrusted.
*/
public byte[] Decrypt(PreKeyWhisperMessage ciphertext, DecryptionCallback callback)
{
lock (SESSION_LOCK)
{
SessionRecord sessionRecord = sessionStore.LoadSession(remoteAddress);
May <uint> unsignedPreKeyId = sessionBuilder.Process(sessionRecord, ciphertext);
byte[] plaintext = Decrypt(sessionRecord, ciphertext.GetWhisperMessage());
callback.HandlePlaintext(plaintext);
sessionStore.StoreSession(remoteAddress, sessionRecord);
if (unsignedPreKeyId.HasValue)
{
preKeyStore.RemovePreKey(unsignedPreKeyId.ForceGetValue());
}
return(plaintext);
}
}
/**
* Decrypt a SenderKey group message.
*
* @param senderKeyMessageBytes The received ciphertext.
* @param callback A callback that is triggered after decryption is complete,
* but before the updated session state has been committed to the session
* DB. This allows some implementations to store the committed plaintext
* to a DB first, in case they are concerned with a crash happening between
* the time the session state is updated but before they're able to store
* the plaintext to disk.
* @return Plaintext
* @throws LegacyMessageException
* @throws InvalidMessageException
* @throws DuplicateMessageException
*/
public byte[] Decrypt(byte[] senderKeyMessageBytes, DecryptionCallback callback)
{
lock (LOCK)
{
try
{
SenderKeyRecord record = senderKeyStore.LoadSenderKey(senderKeyId);
if (record.IsEmpty())
{
throw new NoSessionException("No Sender Key For: " + senderKeyId);
}
SenderKeyMessage senderKeyMessage = new SenderKeyMessage(senderKeyMessageBytes);
SenderKeyState senderKeyState = record.GetSenderKeyState(senderKeyMessage.GetKeyId());
senderKeyMessage.VerifySignature(senderKeyState.GetSigningKeyPublic());
SenderMessageKey senderKey = GetSenderKey(senderKeyState, senderKeyMessage.GetIteration());
byte[] plaintext = GetPlainText(senderKey.GetIv(), senderKey.GetCipherKey(), senderKeyMessage.GetCipherText());
callback.HandlePlaintext(plaintext);
senderKeyStore.StoreSenderKey(senderKeyId, record);
return(plaintext);
}
catch (InvalidKeyException e)
{
throw new InvalidMessageException(e);
}
catch (InvalidKeyIdException e)
{
throw new InvalidMessageException(e);
}
}
}