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Going by the example here: https://bitcoinj.github.io/working-with-contracts

I believe I've done everything correctly. Yet my program fails either to propagate correctly or because of a tx error and I cannot determine why

A few things I believe to be the reason

1) My peergroup.broadcastTransaction(spendTx) is not broadcasting properly 2) A malformed raw transaction or scriptsig ( I assume it is this, but again, no errors) 3) Generally not understanding the best method of linking outputs to inputs and signing them appropriately (for instance, do I use UTXO class, or TransactionSignature) 3) Trying to spend funds from a watched address. I have the necessary keys to unlock the UTXO's but I would like to see if I can spend the funds without the use of the wallet class 4) Multisig support in general for bitcoinj is lacking or incomplete. i hope it's not this as I would really like to get this working. But -- I don't think this is the biggest issue because I ran the unit tests and they still all check out clean.

A step through the code to be thorough:

Create 3 ECKeys for a 2-of-3 multisig contract, put them into a list, create a redeem script that sorts keys in lexicographical order and writes a m-of-n multisigoutputscript, then instantiate a Transaction object and assign it as the OUTPUT that I will be using as my INPUT (amount + redeemscript) AKA the UTXO that I will be spending (EDIT: Quick mention. The ECKeys I'm really using are hardcoded values that I made a while ago, these are for illustration purposes. I also should mention that this is a P2SH multisig, not the raw non-standard multisig.

ECKey keyA = new ECKey();
ECKey keyB = new ECKey();
ECKey keyC = new ECKey();

List<ECKey> keys = ImmutableList.of(key1, key2, key3);

Script script = ScriptBuilder.createRedeemScript(2, keys);
Script scriptPubKey = ScriptBuilder.createP2SHOutputScript(script);

Transaction contract = new Transaction(params);
TransactionOutput multiSigOutput = contract.addOutput(Coin.valueOf(50000), scriptPubKey);

Create a second transaction object that I will be using to assemble the output script AKA the (value + destination) address that i will be signing my UTXO over to. Also where the sigHash is signed by 2 of my keys and added to the scriptSig of the transaction

                        Transaction spendTx = new Transaction(params);
                        Address address = Address.fromBase58(params, "19EfMrs5WkcvtBBnuEqP6v1yppeWww61Kc");
                        Script outputScript = ScriptBuilder.createOutputScript(address);
                        spendTx.addOutput(multiSigOutput.getValue(), outputScript);
//                        System.out.println(spendTx.getOutputs());
                        TransactionInput input = spendTx.addInput(multiSigOutput);

now manually sign the inputs...(signatures are in same order as they are in script)

//sign transaction manually
Sha256Hash sigHash = spendTx.hashForSignature(0, script, Transaction.SigHash.ALL, false);
ECKey.ECDSASignature signature = list.get(0).sign(sigHash);
ECKey.ECDSASignature signature1 = list.get(1).sign(sigHash);
TransactionSignature txSig = new TransactionSignature(signature, Transaction.SigHash.ALL, false);
TransactionSignature txSig1 = new TransactionSignature(signature1, Transaction.SigHash.ALL, false);

...now create multisiginputscript, validate and broadcast tx

                        Script inputScript = ScriptBuilder.createP2SHMultiSigInputScript((ImmutableList.of(txSig, txSig1)));
//                        System.out.println(inputScript);
                        input.setScriptSig(inputScript);
                        input.verify(multiSigOutput);

                        peerGroup.broadcastTransaction(spendTx);

                        System.out.println(kit.peerGroup().getConnectedPeers());
                        System.out.println("transaction broadcasted");

ok...this doesn't propagate, but the verification checks out. and I don't even know if it's so much a network problem as it is a code problem because when I change the value in the output script to > the balance of the UTXO it doesn't throw a InsufficientMoneyException like I imagine it should. I'd show some error logs but there aren't any. The only error is when I change the createmultisiginputscript to createP2SHmultisiginputscript, the console puts out a non-null nulldummy error which I also have problems fixing, so I've never been able to know if changing to that method is the correct fix either. I think I set up the connection to the peergroup correctly as well

File chainFile = new File(this.getFilesDir(), "test.spvchain");
System.out.println("does chainfile exist?"  + chainFile.exists());
if(chainFile.exists()) {
    try {
        SPVBlockStore chainStore = new SPVBlockStore(params, chainFile);
        BlockChain chain = new BlockChain(params, chainStore);
        peerGroup = new PeerGroup(params, chain);
        peerGroup.addPeerDiscovery(new DnsDiscovery(params));
        peerGroup.startAsync();
    } catch (BlockStoreException e) {
        e.printStackTrace();
    }

So I don't really get it... I've come to the conclusion my understanding is off somehow. Sorry for the confusing long post. It's been days. Can anyone help?

EDIT: Here's the raw transaction

In hex: 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

In logs:

fbb119d8990cd3912a9ec0118fe3ad8ad61a8388e4a13dd342d9eb67aacfdc65

01-12 17:49:20.670 2507-2507/com.cryptoapp.app I/System.out: in 0[] PUSHDATA(71)[3044022022b97b9372d35acaea70f3735dee290f5697cab7b5d6be6f7cdfe31139fba4f90220651091b83570843d4fe8afe02d81417194908b0f6af6f8f3b8f1ad020592409f01] PUSHDATA(71)[3044022036eff4f54b8bf3f834f7bb6e417a04a6a696047f5c75a896c6f9b624ad87680a02200bf2115b64b3b15647178b69151d4588d8a4ade16a4d66e375d0e1265c79fad601] PUSHDATA1[5221025ab78e076801b45ccb2172bce562103cce1714edbeb02ce6123ce1235eb08c762102d1b74577050b696d5886a7afa61d099ea7ab0a3797766f9819dbd72526b0ce512103facf04db5d9bee657151e30c21e839489c326a277891ebcf75b736ec1e17fc1f53ae] 0.0005 BTC 01-12 17:49:20.670 2507-2507/com.cryptoapp.app I/System.out: outpoint:c33858b433ef445db35a84daa4da772895df7f03af4b31f21cfa199ea1c017d9:0 hash160:6d49586d7529626aaab49812bcd7839aee7e5800 01-12 17:49:20.670 2507-2507/com.cryptoapp.app I/System.out: out DUP HASH160 PUSHDATA(20)[5a566f4eda18e818b8d5ca04ee7c5fa3cfbf0e00] EQUALVERIFY CHECKSIG 0.0005 BTC 01-12 17:49:20.670 2507-2507/com.cryptoapp.app I/System.out: fee 0.00 BTC/kB, 0.00 BTC for 337 bytes 01-12 17:49:20.670 2507-2507/com.cryptoapp.app I/System.out: prps UNKNOWN

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1 Answer 1

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A couple comments from inspecting the Transaction data you posted.

1) I checked the UTXO you are spending from, which is UTXO

  • 9e7562d19165077d566af47bfbc18283629ed6799da8862660dfb037c353de11
  • Index 0

However, your transaction input is currently referencing the following UTXO:

  • c33858b433ef445db35a84daa4da772895df7f03af4b31f21cfa199ea1c017d9
  • Index 0

Which is not a confirmed transaction on main net.

2) Your input script seems properly formed to spend your P2SH(Multisig) output:

  • zero
  • [3044022022b97b9372d35acaea70f3735dee290f5697cab7b5d6be6f7cdfe31139fba4f90220651091b83570843d4fe8afe02d81417194908b0f6af6f8f3b8f1ad020592409f01]
  • [3044022036eff4f54b8bf3f834f7bb6e417a04a6a696047f5c75a896c6f9b624ad87680a02200bf2115b64b3b15647178b69151d4588d8a4ade16a4d66e375d0e1265c79fad601]
  • [2 [025ab78e076801b45ccb2172bce562103cce1714edbeb02ce6123ce1235eb08c76] [02d1b74577050b696d5886a7afa61d099ea7ab0a3797766f9819dbd72526b0ce51] [03facf04db5d9bee657151e30c21e839489c326a277891ebcf75b736ec1e17fc1f] 3 checkmultisig]

The final element is the embedded script, and should hash to the 20B digest in your UTXO you are spending: it does indeed hash160 correctly to 6d49586d7529626aaab49812bcd7839aee7e5800.

For your reference the P2SH(Multisig) output script of your UTXO is: "hash160 [6d49586d7529626aaab49812bcd7839aee7e5800] equal", note that the hashes are the same, so that's good.

3) You haven't included a fee in your transaction. The output amount of 50000 sats is identical to the UTXO amount. There needs to be a minimum fee for this transaction to be accepted by the mempool.

I hope this helps.

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  • Thanks for your comment. It does verify. If it did not it would throw an error.
    – Stephen
    Jan 12, 2019 at 7:42
  • Script script = ScriptBuilder.createRedeemScript(2, keys); and Script script = ScriptBuilder.createMultiSigOutputScript(2, keys); are the same thing except createRedeemScript puts the keys in lexicographical order but it returns the same function
    – Stephen
    Jan 12, 2019 at 7:44
  • Can u post both raw tx here, would be easier to help debug.
    – James C.
    Jan 12, 2019 at 7:44
  • Ah ok. So u still need to confirm the first tx before broadcasting the second.
    – James C.
    Jan 12, 2019 at 7:45
  • So I'm a little bit confused. I thought the first tx was an output script which creates the template for the UTXO as context for the second transaction(and the verification). So you're saying I have to broadcast where i created the multisig script and then broadcast the spend as well?
    – Stephen
    Jan 12, 2019 at 7:48

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