With the BCH signer done, here is a guide on how to use it and keeping your stash secure.
-------- The signer --------In order to sign for BCH, you have to pick your signer manually. This is a new feature, and is only available in Expert mode, so first thing first, set user mode to Expert.
To pick the signer, you need to get to the "Confirm Transaction" dialog. Once there, you should see the signer select frame, click it and pick the signer for the chain you want to spend on. The default option only picks between Bitcoin signers, to sign for BCH you
HAVE to pick the BCH signer manually.
Screenshots for the good measure:
https://imgur.com/a/9zXGDOnce you've picked the signer, the rest is business as usual. Note that this step only occurs at the point of signing, i.e. if you sign offline, you have to pick the signer on your offline machine.
-------- Security --------The process is relatively safe. If you mess up and pick the wrong signer for you chain, the transaction will be invalid for that chain anyways.
That transaction is valid for the chain signer is for however, example:Armory is running against a BCH node. You create a tx and sign it with a Bitcoin signer. That transaction will fail to broadcast to the BCH network. However, if you try to broadcast this same transaction with an instance of Armory connected to a Bitcoin node, it will succeed and your coins will be moved on that chain.
This may sound confusing but this is how Armory operates by design, it trusts the underlying node to be honest and the Bcash devs made a point of not changing network ports, magic number identifiers nor script hash prefixes, so you end up with this mess.
As for why I didn't go further out of my way to try and make this distinction stronger in my own code, I'm trying to think for the future with all changes to mission critical code (such as signers), and let's be real, Bcash has no future. Therefor the changes were minimal, with an explicitly paying attention to:
1) Trying to salvage as much code as possible from this effort (OP_RETURN outputs and signer selection).
2) Making it easy to prune the useless bits once miners pull the plug on this nonsense.
3) Be prepared for the next gonzo debacle (2x?).
At any rate, if you do not care about Bcash, this feature is transparent to you, as the signer will always default to Bitcoin.
-------- Splitting your coins ---------As stated previously, BCH sigs are invalid on the Bitcoin chain, and vice versa. Therefor there's nothing more to splitting your prefork coins but to spend them post fork.
-------- Testing --------I've moved coins on the BCH chain. Here's a tx created with Armory:
2cc2b1f4578e6c0b42c5de396ca43eb0fe6868509bd19d9bd5e14a0b4f2c5166
I've also used the opportunity to test the OP_RETURN feature on a mainnet. If you inspect the transaction, you should be able to read "signed with armory" in the op_return message.
For the more paranoid, you can trace the history of the outpoint on the Bitcoin chain and verify that it has been spent to a completely different transaction, therefor demonstrating the split. The order I went was Bitcoin tx first, Bcash second, but it should work the other way around as well.
-------- Privacy ---------In order to reduce privacy leakage, you should pick non KYC pure crypto exchanges. In this case, spend UTXO per UTXO in order to not link your coins on chain. If you're using a KYC exchange, it doesn't matter as much, as the exchange knows these coins are linked and who controls them, even though it wouldn't be obvious on chain if you went a UTXO at a time.
Whether you have sent your coins to a KYC exchange or not, you want to cycle your wallets on the other chain afterwards, i.e. if you dumped BCH, you want to move all these coins on BTC chain to a fresh wallet.
The reason for this is that your public keys will be exposed on at least one chain. One of the security layers of Bitcoin is that public keys are behind hashes up until you spend the coin. Once you sign coins on one of the chains, you lose this layer. This is a major reason why you do not reuse addresses in Bitcoin. This is particularly relevant if you have coins in long term cold storage: cycle them if you touch the keys!
As for how to cycle your wallets, it depends on the scenario:
1) If you used a KYC exchange, create a new wallet and send coins over whichever way you want, you have no privacy at this point. To regain fungibility, you will have to mix your coins or swap to fungible alt coins and back. This is out of the scope of this post, do your research if you value your financial privacy.
2) You used a non KYC exchange or some sort of cross chain swap scheme. You should move your coins to your new wallet utxo per utxo, or (1 in -> 2-3 outs), over the course of several weeks.
-------- Requirements --------You need to update
both your signer and online machine with a version of Armory capable to sign for BCH in order to spend the coins.
You need a copy of the chain, a running node and DB
per side of the fork. You cannot mix
ANY of these or you will corrupt your data. As a safety, make a backup of your Bitcoin chain before fiddling with the BCH stuff.
-------- Tricks --------If you want to dump BCH but don't want to bother with the BCH node/don't trust their code, you can get around it with this trick:
1) You know all your prefork coins are also available on the BCH chain, therefor you only need blockchain data up to the fork point to move these coins.
2) You have all this data already in the form of the Bitcoin blockchain pre fork, so why not just use that?
3) You'll want to create a copy of your blockchain data then remove blkXXXXX.dat files up until the fork point . I don't know which file this is, something around 950~960, I'm sure someone will figure out the exact file. Note that if you did not move any coins post fork yet, you do not need to delete anything.
4) With this done, you want to sync a fresh DB against this blockchain folder. Do not run a node against it, just start ArmoryDB against this folder, then start ArmoryQt, it will pick up on that DB.
5) Once you're synced (it will show you as offline), you can create your transactions. You should pick utxos manually and keep track of them so as to not create conflicting transactions.
6) Once your tx is ready, make sure to create it as unsigned, even if your private keys are online. You will get a blob of text that you can feed back into the offline tx GUI. There you will get to sign the tx (make sure to pick the BCH miner), and you will get another blob of text. On the right side of that dialog, you will have a button that's called "Copy Raw Tx (Hex)". This is what you are after. This hex string is your signed tx.
7) With the signed tx, all you need now is some online service that will broadcast it to the BCH network for you, and voila.
-------- Advice --------At first, before you try to fund an exchange account, send coins back to yourself on both chains and wait for a few confirmations to be sure you aren't shooting yourself in the foot. Cross check on the other chain to make sure you send the coins to the chain you intended.
-------- Disclaimer --------It only makes sense but I'll remind it here: use this code at your own risk!
