"Run the numbers" shall use muhash

[carnhofdaki]

Describe the bug
Or it should be at least possible to set muhash when calling gettxoutsetinfo. Using the coinstatsindex make it take a second instead of minutes.

To Reproduce
Steps to reproduce the behavior:

1. Go to http://127.0.0.1:25441/wallets/wallet/<name_of_wallet>/receive/
2. Click on 'Run the numbers!'
3. It takes too long since running gettxoutsetinfo without muhash parameter is very slow. With muhash parameter, one has to have the small (currently 131MB) coinstatsindex.

Expected behavior
"Run the numbers" should take less than a second. It should be immediate.

$ time bitcoin-cli gettxoutsetinfo muhash
{
  "height": 775192,
  "bestblock": "000000000000000000071fafcd59fb89454864d51afc206559111381b22cb630",
  "txouts": 83747992,
  "bogosize": 6243049379,
  "muhash": "fae547fb57efe29fcb36c9caf39114543c5d827d8b0831147ad0f0136dc90a22",
  "total_amount": 19282240.19258451,
  "total_unspendable_amount": 216.05741549,
  "block_info": {
    "prevout_spent": 6465.64625252,
    "coinbase": 6.41212171,
    "new_outputs_ex_coinbase": 6465.48413081,
    "unspendable": 0.00000000,
    "unspendables": {
      "genesis_block": 0.00000000,
      "bip30": 0.00000000,
      "scripts": 0.00000000,
      "unclaimed_rewards": 0.00000000
    }
  }
}
    0m00.02s real     0m00.00s user     0m00.00s system

Desktop (please complete the following information):

• Where is your node running: local full node (plain Bitcoin Core on Linux, no bundles)
• Where is your specter running: pip3 local Linux x86_64
• Browser Chrome
• Specter Version 1.14.5

[moneymanolis]

Thanks for this interesting issue, I was not aware of that.

To clarify @carnhofdaki, using gettxoutsetinfo with muhash and coinstatsindex=1 in the bitcoin.conf gives the super fast result. But, what happens in the case of just using gettxoutsetinfo with muhash without coinstatsindex=1 in the bitcoin.conf (since we have no "control" over which bitcoin config the users are using)? Is it still faster, if so by how much approximately?

Here is some background for others looking at this issue:
https://gist.github.com/fjahr/fa4892874b090d3a4f4fccc5bafa0210

"The RPC call gettxoutsetinfo returns (among other things) a hash of the whole UTXO set which can be used as an efficient way to compare your UTXO set with your peers. Since the hash is calculated in real time this call can take several minutes depending on your hardware. A solution to this was presented on the Bitcoin Mailing List by Pieter Wuille. He discusses MuHash and ECMH as potential homomorphic hashing function solutions to implement the UTXO set hash as a rolling hash which could be efficiently updated with every new block by adding hashes of new UTXOs and removing hashes of spent UTXOs. The resulting hash of each new chainstate could be cached and returned instantly without spending CPU cycles."

[carnhofdaki]

@moneymanolis On a node with coinstatsindex=0 this is the result:

$ bitcoin-cli gettxoutsetinfo muhash 783937
error code: -8
error message:
Querying specific block heights requires coinstatsindex