Tapsim is a simple tool built in Go for debugging Bitcoin Tapscript transactions. It's aimed at developers wanting play with Bitcoin script primitives, aid in script debugging, and visualize the VM state as scripts are executed.
Tapsim hooks into the btcd script execution engine to retrieve state at every step of script execution.
The script execution is controlled using the left/right arrow keys.
Currently visualized during execution:
- Script
- Stack
- Altstack
- Witness stack
Before installing Tapsim, please ensure you have the latest version of Go (Go 1.20 or later) installed on your computer.
git clone https://github.com/halseth/tapsim.git
cd tapsim
go build ./cmd/tapsimAlso found in the cmd folder are a few tools useful for certain script
releated tasks:
keys: generates random key pairsmerkle: builds merkle treesscriptnum: convert to and from the Bitcoin CScriptNum formattweak: tweak public keys with data and taproot
$ ./tapsim -h
NAME:
tapsim - parse and debug bitcoin scripts
USAGE:
tapsim [global options] command [command options] [arguments...]
COMMANDS:
parse
execute
help, h Shows a list of commands or help for one command
GLOBAL OPTIONS:
--help, -h show help (default: false)$ ./tapsim execute --script "OP_HASH160 79510b993bd0c642db233e2c9f3d9ef0d653f229 OP_EQUAL" --witness "54"
Script: OP_HASH160 79510b993bd0c642db233e2c9f3d9ef0d653f229 OP_EQUAL
Witness: 54
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
script | stack | alt stack | witness
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
OP_HASH160 | 01 | |
OP_DATA_20 0x79510b993bd0c642db23...f229| | |
OP_EQUAL | | |
> | | |
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
script execution verified$ ./tapsim execute -h
NAME:
tapsim execute
USAGE:
tapsim execute [command options] [arguments...]
OPTIONS:
--script value filename or output script as string
--scripts value list of filenames with output scripts to assemble into a taptree
--scriptindex value index of script from "scripts" to execute (default: 0)
--witness value filename or witness stack as string
--non-interactive, --ni disable interactive mode (default: false)
--no-step, --ns don't show step by step, just validate (default: false)
--privkeys value specify private keys as "key1:<hex>,key2:<hex>" to sign the transaction. Set <hex> empty to generate a random key with the given ID.
--inputkey value use specified internal key for the input
--outputkey value use specified internal key for the output
--outputs value specify taproot outputs as "<pubkey>:<value>"
--tagfile value optional json file map from hex values to human-readable tags
--colwidth value output column width (default: 40)
--rows value max rows to print in execution table (default: 25)
--skip value skip aheead (default: 0)
--help, -h show help (default: false)In addition to the regular Bitcoin tapscript opcodes, tapsim has added support for scripts using
- OP_CAT
- OP_CHECKCONTRACTVERIFY
Contributions to Tapsim are welcomed. Please open a pull request or issue.
This project is heavily inspired by the excellent btcdeb.
Tapsim is licensed under the MIT License - see the LICENSE.md file for details.