I'm using the Golang btcsuite/btcd library to write a Bitcoin app that creates custom OP_RETURN TXs in the blockchain.

I understand Bitcoin at a high-level (proof-of-work consensus, Merkle trees, membership, signatures, etc.), but I'm getting lost in the (unnecessarily?) complicated details of its RPC interface.

I was writing code in Go for creating a custom transaction with 1 input and 2 outputs (an OP_RETURN output and a change output). Here are my questions:

  1. Is this considered a raw transaction? (If so, what exactly constitutes a raw transaction? Is it all transactions that don't get created via the sendfrom/sendmany/sendtoaddress RPC?)
  2. What's the difference between getnewaddress and getrawchangeaddress at a semantic level? It seems that both generate a key-pair, but why is there a need for two different calls?
  3. If I'm creating a raw transaction as described above, should I send the change to a getnewaddress key or a getrawchangeaddress key?

Thank you,
Alin

up vote 0 down vote accepted
  1. The rawtransaction interface accepts and returns "raw" hex encoded p2p compatible transactions. Using the non-rawtransaction methods (like sendtoaddres, will not give you the possibility to inspect or alter the created bytearray.

  2. The getrawchangeaddress method will retrieve a key from the keypool and return its pubkey (encoded into an p2pkh address). Unlike getrawchangeaddress, gewnewaddress will create an address book entry that will allow you better ways to inspect/distinct what funds you have received with that address and therefore increases the chance of a reused address.

  3. You should use getrawchangeaddress if you like to use the given address as a change output for your rawtransaction.

  • Thank you! Cool, so when people talk about a raw transaction they mean any custom-built transaction, as opposed to a fixed kind as suggested by APIs like this one. Did you mean to write "unlike" instead of "unless then"? – Alin Tomescu Jul 13 '16 at 16:00
  • Question: If I use getrawchangeaddress to send the change, the change UTXO of the raw OP_RETURN TX I created doesn't show up in my listunspent query. Why is that? I would like to continue spending that change, by easily finding the UTXO for it. Should I use getnewaddress instead? Is there something wrong with that? This is where I am confused about the two. – Alin Tomescu Jul 13 '16 at 16:03
  • (This is in regtest mode and I've generated a new block for the raw TX, plus another 10 blocks after it.) – Alin Tomescu Jul 13 '16 at 16:09
  • Answer: Actually, I just realized the raw TX was not being included in a block because I set the transaction's fee to zero. I was able to mine it in a block and send the change to a getnewaddress PK. I am seeing the change in listunspent now. Will check if getrawchangeaddress works as well... – Alin Tomescu Jul 13 '16 at 18:26
  • Both getnewaddress and getrawchangeaddress work except getnewaddress can associate the PK with an 'account.' However, since accounts are deprecated, I will stay away from them. Still unclear why both calls exist, especially if accounts are being deprecated: the corresponding SK needs to be added to the wallet by both of them, so what's the difference between them? – Alin Tomescu Jul 14 '16 at 22:09

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