I am new to bitcoins, I want to create an offline wallet on Android, to scan transaction QR code from online Desktop wallet, Sign that transaction with private key on my offline wallet.

1 Creating offline wallet. 2.Signing transaction offline with private key.

I want to sign transaction and generate QR code from that sign transaction.But after signing i get a sha256 in this form “MEQCIGBVDN/PkbESZdWkG6/KzrDRAEpDXVdsjKMzErBfFIWYAiA8JJOv97Dlp8Acg/L8JHI3RzoW eYNxPW1Lx4wQaORNNQ==”, so what will i do with this. So please help and review my code. Is my signing process ok or if not please comeup with some code.Thanks

So for i did the following.

// For creating wallet

private void InitilizeWallet()

throws IOException {

    BriefLogFormatter.init();      params = TestNet3Params.get();      filePrefix = "forwarding-service-testnet";      walletAppKit = new WalletAppKit(params, getCacheDir(), filePrefix) {         @Override         protected void onSetupCompleted() {             if (wallet().getKeyChainGroupSize() < 1)                 wallet().importKey(new ECKey());              deterministicKey = wallet().getWatchingKey().dropPrivateBytes();             deterministicKey = HDKeyDerivation.createMasterPubKeyFromBytes(deterministicKey.getPubKey(), deterministicKey.getChainCode());             xPublicKey = deterministicKey.serializePubB58(params);    privateKey=wallet().getKeyByPath(DeterministicKeyChain.ACCOUNT_ZERO_PATH).getPrivateKeyAsWiF(params);             Log.e("key", xPublicKey.toString());             Log.e("privatekey", privateKey.toString());          }     };       if (params == RegTestParams.get()) {         // Regression test mode is designed for testing and development only, so there's no public network for it.         // If you pick this mode, you're expected to be running a local "bitcoind -regtest" instance.         walletAppKit.connectToLocalHost();     }     // Download the block chain and wait until it's done.       walletAppKit.startAsync();     walletAppKit.awaitRunning();  } 

And for signing transaction i do the following.

public void Createtransictionhash(String recipientAddress, String amount) {

    try {            // i am getting address and coins from QR code          SendRequest request = SendRequest.to(Address.fromBase58(params,          recipientAddress), Coin.parseCoin(amount));             Signingtrasaction(MainActivity.privateKey,request.tx.getHashAsString());          Log.e("txhash", request.tx.getHashAsString());      } catch (Exception e) {         Log.e("msgError", e.getMessage().toString());         Toast.makeText(getApplicationContext(), " Version code of address did not match", Toast.LENGTH_SHORT).show();      } }  public void Signingtrasaction(String wif, String msg) {     try {           // message (hash) to be signed with private key         //String msg = "15953935a135031bfec37d36a9d662aea43e1deb0ea463d6932ac6e537cb3e81";         //my hash = 09b14f746bd0a93b71907ba0070a103adbee7b1a260e053a21aa0b660ad8de57         // an example of WiF for private key (taken from 'Mastering Bitcoin')        // wif ="KxFC1jmwwCoACiCAWZ3eXa96mBM6tb3TYzGmf6YwgdGWZgawvrtJ";          // creating a key object from WiF         DumpedPrivateKey dpk = DumpedPrivateKey.fromBase58(params, wif);         ECKey key = dpk.getKey();          // checking our key object        // NetworkParameters main = MainNetParams.get();         String check = key.getPrivateKeyAsWiF(params);         System.out.println(wif.equals(check));  // true         Log.e("wif check", String.valueOf(wif.equals(check)));         // creating Sha object from string         Sha256Hash hash = Sha256Hash.wrap(msg);          // creating signature         ECKey.ECDSASignature sig = key.sign(hash);          // encoding         byte[] res = sig.encodeToDER();          // converting to hex         //String hex = DatatypeConverter.printHexBinary(res);         // String hex = new String(res);         String hex = android.util.Base64.encodeToString(res, 16);          Log.e("sigendTransiction", hex.toString());          Log.e("decrypttx",""+ Hex.decode(sig.encodeToDER()));      } catch (Exception e) {   //signingkey = ecdsa.from_string(privateKey.decode('hex'), curve=ecdsa.SECP256k1)         Log.e("signing exception", e.getMessage().toString());     } }