/**
* Takes an UnencryptedMsg object and does all the work necessary to transform it into an
* EncyrptedMsg object that is ready to be serialised and sent out to the Bitmessage network. The
* two major parts of this process are encryption and proof of work. <br>
* <br>
* <b>NOTE!</b> Calling this method results in proof of work calculations being done for the
* message. This can take a long time and lots of CPU power!<br>
* <br>
*
* @param message - The original plain text Message object, provided so that its status can be
* updated during the process
* @param unencMsg - The UnencryptedMsg object to be encrypted
* @param toPubkey - The Pubkey object containing the public encryption key of the intended
* message recipient
* @param doPOW - A boolean value indicating whether or not POW should be done for this message
* @param timeToLive - The 'time to live' value (in seconds) to be used in creating this msg
* @return A Msg object containing the encrypted message data
*/
private BMObject constructMsg(
Message message, UnencryptedMsg unencMsg, Pubkey toPubkey, boolean doPOW, long timeToLive) {
// Reconstruct the ECPublicKey object from the byte[] found the the relevant PubKey
ECPublicKey publicEncryptionKey =
new KeyConverter().reconstructPublicKey(toPubkey.getPublicEncryptionKey());
// Construct the payload to be encrypted
byte[] msgDataForEncryption = constructMsgPayloadForEncryption(unencMsg);
// Update the status of this message displayed in the UI
String messageStatus = App.getContext().getString(R.string.message_status_encrypting_message);
MessageStatusHandler.updateMessageStatus(message, messageStatus);
// Encrypt the payload
CryptProcessor cryptProc = new CryptProcessor();
byte[] encryptedPayload = cryptProc.encrypt(msgDataForEncryption, publicEncryptionKey);
// Create a new Msg object and populate its fields
BMObject msg = new BMObject();
msg.setBelongsToMe(
true); // NOTE: This method assumes that any message I am encrypting 'belongs to me' (i.e.
// The user of the application is the author of the message)
msg.setExpirationTime(unencMsg.getExpirationTime());
msg.setObjectType(unencMsg.getObjectType());
msg.setObjectVersion(unencMsg.getObjectVersion());
msg.setStreamNumber(toPubkey.getStreamNumber());
msg.setPayload(encryptedPayload);
if (doPOW) {
MessageStatusHandler.updateMessageStatus(
message, App.getContext().getString(R.string.message_status_doing_pow));
// Do proof of work for the Msg object
Log.i(TAG, "About to do POW calculations for a msg that we are sending");
byte[] powPayload = constructMsgPayloadForPOW(msg);
long powNonce =
new POWProcessor()
.doPOW(
powPayload,
unencMsg.getExpirationTime(),
toPubkey.getNonceTrialsPerByte(),
toPubkey.getExtraBytes());
msg.setPOWNonce(powNonce);
} else {
msg.setPOWNonce(
(long) 0); // If POW is not to be done for this message, set the powNonce as zero for now.
}
return msg;
}
/**
* Constructs an UnencryptedMsg object from a given Message object. Used when sending a message.
* <br>
* <br>
* <b>NOTE!</b> Calling this method results in proof of work calculations being done for the
* acknowledgement data of the message. This can take a long time and lots of CPU power!<br>
* <br>
* <b>NOTE!</b> Calling this method can result in requests to a Bitseal server to retrieve pubkey
* data. These requests may take some time to complete!
*
* @param message - The Message object to convert into an UnencryptedMsg object
* @param toPubkey - A Pubkey object containing the public keys of the address the message is
* being sent to
* @param doPOW - A boolean indicating whether or not POW should be done for msgs generated during
* this process
* @param timeToLive - The 'time to live' value (in seconds) to be used in processing this message
* @return An UnencryptedMsg object based on the supplied Message object.
*/
private UnencryptedMsg constructUnencryptedMsg(
Message message, Pubkey toPubkey, boolean doPOW, long timeToLive) {
String messageSubject = message.getSubject();
String messageBody = message.getBody();
// First let us check that the to address and from address Strings taken from the Message object
// are in fact valid Bitmessage addresses
String toAddressString = message.getToAddress();
String fromAddressString = message.getFromAddress();
AddressProcessor addProc = new AddressProcessor();
if (addProc.validateAddress(toAddressString) != true) {
throw new RuntimeException(
"During the execution of constructUnencryptedMsg(), it was found that the 'to' address in the supplied Message was not a valid Bitmessage address");
}
if (addProc.validateAddress(fromAddressString) != true) {
throw new RuntimeException(
"During the execution of constructUnencryptedMsg(), it was found that the 'from' address in the supplied Message was not a valid Bitmessage address");
}
// Now that we have validated the to address and the from address, let us retrieve or create
// their corresponding Address and Pubkey objects.
Address fromAddress = null;
AddressProvider addProv = AddressProvider.get(App.getContext());
ArrayList<Address> retrievedAddresses =
addProv.searchAddresses(AddressesTable.COLUMN_ADDRESS, fromAddressString);
if (retrievedAddresses.size() != 1) {
Log.e(
TAG,
"There should be exactly 1 record found in this search. Instead "
+ retrievedAddresses.size()
+ " records were found");
} else {
fromAddress = retrievedAddresses.get(0);
}
// Now we need to get the behaviour bitfield from the pubkey which corresponds to the from
// address, so let us retrieve that pubkey.
PubkeyProvider pubProv = PubkeyProvider.get(App.getContext());
ArrayList<Pubkey> retrievedPubkeys =
pubProv.searchPubkeys(
PubkeysTable.COLUMN_CORRESPONDING_ADDRESS_ID, String.valueOf(fromAddress.getId()));
Pubkey fromPubkey = null;
if (retrievedPubkeys.size() == 1) {
fromPubkey = retrievedPubkeys.get(0);
} else if (retrievedPubkeys.size() > 1) // If there are duplicate pubkeys for this address
{
Log.e(
TAG,
"There should be exactly 1 record found in this search. Instead "
+ retrievedPubkeys.size()
+ " records were found");
// Delete all but the most recent of the duplicate pubkeys
long firstPubkeyTime = retrievedPubkeys.get(0).getExpirationTime();
Pubkey pubkeyToKeep = retrievedPubkeys.get(0);
for (Pubkey p : retrievedPubkeys) {
if (p.getExpirationTime() > firstPubkeyTime) {
pubkeyToKeep = p;
}
}
for (Pubkey p : retrievedPubkeys) {
if (p.equals(pubkeyToKeep) == false) {
pubProv.deletePubkey(p);
}
}
// Use the most recent of the duplicate pubkeys
fromPubkey = pubkeyToKeep;
}
if (fromPubkey == null) {
Log.e(
TAG,
"Could not find the Pubkey which corresponds to the from address, even though it should be one of our own. Something is wrong!");
Log.d(TAG, "Regenerating the Pubkey for the from address");
fromPubkey =
new PubkeyGenerator()
.generateAndSaveNewPubkey(
fromAddress); // If we can't find the pubkey we need then let us generate it again
}
// Now extract the public signing and public encryption keys from the "from" pubkey
// If the public signing and encryption keys taken from the Pubkey object have an "\x04" byte at
// their beginning, we need to remove it now.
byte[] publicSigningKey = fromPubkey.getPublicSigningKey();
byte[] publicEncryptionKey = fromPubkey.getPublicEncryptionKey();
if (publicSigningKey[0] == (byte) 4 && publicSigningKey.length == 65) {
publicSigningKey = ArrayCopier.copyOfRange(publicSigningKey, 1, publicSigningKey.length);
}
if (publicEncryptionKey[0] == (byte) 4 && publicEncryptionKey.length == 65) {
publicEncryptionKey =
ArrayCopier.copyOfRange(publicEncryptionKey, 1, publicEncryptionKey.length);
}
// Generate the ack data (32 random bytes)
byte[] ackData = new byte[32];
new SecureRandom().nextBytes(ackData);
// Generate the full ack Message that will be included in this unencrypted msg.
// NOTE: Calling generateFullAckMessage() results in Proof of Work calculations being done for
// the
// acknowledgement Message. This can take a long time and lots of CPU power!
byte[] fullAckMessage =
generateFullAckMessage(message, ackData, fromPubkey.getStreamNumber(), doPOW, timeToLive);
Log.d(TAG, "Full ack Message: " + ByteFormatter.byteArrayToHexString(fullAckMessage));
// Create the single "message" text String which contains both the subject and the body of the
// message
// See https://bitmessage.org/wiki/Protocol_specification#Message_Encodings
String messsageText = "Subject:" + messageSubject + "\n" + "Body:" + messageBody;
// Now create the UnencryptedMsg object and populate its fields.
UnencryptedMsg unencMsg = new UnencryptedMsg();
unencMsg.setBelongsToMe(true);
unencMsg.setExpirationTime(TimeUtils.getFuzzedExpirationTime(timeToLive));
unencMsg.setObjectType(OBJECT_TYPE_MSG);
unencMsg.setObjectVersion(OBJECT_VERSION_MSG);
unencMsg.setStreamNumber(toPubkey.getStreamNumber());
unencMsg.setSenderAddressVersion(fromPubkey.getObjectVersion());
unencMsg.setSenderStreamNumber(fromPubkey.getStreamNumber());
unencMsg.setBehaviourBitfield(fromPubkey.getBehaviourBitfield());
unencMsg.setPublicSigningKey(publicSigningKey);
unencMsg.setPublicEncryptionKey(publicEncryptionKey);
unencMsg.setNonceTrialsPerByte(fromPubkey.getNonceTrialsPerByte());
unencMsg.setExtraBytes(fromPubkey.getExtraBytes());
unencMsg.setDestinationRipe(new KeyConverter().calculateRipeHashFromPubkey(toPubkey));
unencMsg.setEncoding(MESSAGE_ENCODING_TYPE);
unencMsg.setMessageLength(
messsageText.getBytes()
.length); // We have to use the byte length rather than the string length - some
// characters take more bytes than others
unencMsg.setMessage(
messsageText
.getBytes()); // PyBitmessage also uses UTF-8 as its character set, so this ought to be
// adequate
unencMsg.setAckLength(fullAckMessage.length);
unencMsg.setAckMsg(fullAckMessage);
// Save the acknowledgment data to the database so that when we receive the acknowledgment for
// this message we will recognise it
Payload ackPayload = new Payload();
ackPayload.setBelongsToMe(true); // i.e. This is an acknowledgment created by me
ackPayload.setPOWDone(true);
ackPayload.setAck(true); // This payload is an acknowledgment
ackPayload.setType(
Payload.OBJECT_TYPE_MSG); // Currently we treat all acks from other people as msgs. Strictly
// though they can be objects of any type, so this may change
ackPayload.setPayload(ackData);
PayloadProvider payProv = PayloadProvider.get(App.getContext());
long ackPayloadId = payProv.addPayload(ackPayload);
// Set the "ackPayloadId" field of the original Message object so that we know which Message
// this ack data is for
message.setAckPayloadId(ackPayloadId);
MessageProvider msgProv = MessageProvider.get(App.getContext());
msgProv.updateMessage(message);
// Now create the signature for this message
SigProcessor sigProc = new SigProcessor();
byte[] signaturePayload = sigProc.createUnencryptedMsgSignaturePayload(unencMsg);
byte[] signature = sigProc.signWithWIFKey(signaturePayload, fromAddress.getPrivateSigningKey());
unencMsg.setSignature(signature);
unencMsg.setSignatureLength(signature.length);
return unencMsg;
}
