Build, sign and send Bitcoin transaction

[gratten]

Need to introduce Bitcoin transaction functionality that includes an OP_RETURN containing the user-submitted "stamp" test.

See OP_RETURN.py for some preliminary experimentation with a cli tool script.

This functionality will need to scan the database at a regular time interval. If there are any "target blockheights" which match the current blockheight - 1, a transaction which includes an OP_RETURN containing the corresponding text will need to be built, signed and sent to the Bitcoin network with an appropriate transaction fee to be mined in the next block.

[gratten]

Might be worth looking into including nLockTime when building the transaction.

[gratten]

made some progress on this. still getting a failed broadcast tho. see below for error:

2025/01/16 19:53:02 Failed to broadcast transaction: -26: mandatory-script-verify-flag-failed (Script failed an OP_EQUALVERIFY operation)

[gratten]

the transaction is being built, signed and broadcasted without errors. I need to spend some more time validating that I'm building the transaction correctly

I wrote blockchain.py to help analyze the transaction after it's broadcasted to the network.

[gratten]

need to read up more on time locks...

https://medium.com/summa-technology/bitcoins-time-locks-27e0c362d7a1

[gratten]

Update - 1/30/25

• added logic to distinguish when a user enters a past date or future date and behave accordingly
  • if past date, app works as normal (binary search on blockchain to return corresponding blockheight)
  • if future date, app estimates a target blockheight and presents the user with a text input field
• implemented a database to store the target date, target blockheight, and "stamp" aka user-entered text to be included in the OP_RETURN upon submission of the "stamp" input field
• added /stamps page to display target blockheight, user-submitted "stamps", and transaction ID after broadcast
• implemented building, signing and broadcasting of a bitcoin transaction containing the "stamp" in an OP_RETURN
• implemented a function to monitor target blockheights in the database and compare to the the current blockheight - when a match is found the transaction is broadcasted and /stamps page is updated with the transaction ID
• added logic to check if a transaction has been mined yet, if so indicated with green text on the /stamps page
• began testing with testnet today, successfully broadcasted a few transactions to the network that were eventually mined/confirmed
  • https://mempool.space/testnet/tx/3d4d2d495b7a205817bbd362f8ac3d32d104bd320bc0fdcd5faa6f9e78e93503
  • https://mempool.space/testnet/tx/390c5f07bee6efb09d32cd1a4ecd6cd53999d9ba58061ac79cffd9aed6c41b81
• following data on the site is dynamically rendered via HTMX, polling the server every 3 seconds:
  • current blockheight and date the block was mined
  • blockheight or blockheight estimate corresponding to user-submitted date
  • stamp submission text field
  • data in table on /stamps page, including transaction ID after broadcast and green text after transaction is mined