Hashmal - Transaction Script IDE (alpha)

[Kefkius]

Hashmal

Transaction Script IDE (Github | IRC)

Hashmal is an IDE for Bitcoin transaction scripts. Its purpose is to make it easier to write, evaluate, and learn about transaction scripts. There are very few tools that help people learn about how transaction scripts work; hopefully Hashmal can do this.

Demonstration of stack evaluation.

Hashmal is intended for cryptocurrency developers and power users. It uses python-bitcoinlib for most of its functionality.

Key Features

• Write scripts in human-readable form.
• Observe the stack as scripts are executed.
• See explanations of script operations as they are evaluated.

Notice

Hashmal is a project in its infancy. Please be careful if you intend to use any scripts you make in Hashmal with an actual blockchain. This is alpha software.

You can download Hashmal from Github.

[1714977819]

1714977819

[1714977819]

1714977819

[1714977819]

1714977819

[1714977819]

1714977819

[Uptrenda]

First POST and OP congratulations because you just solved a problem that every Bitcoin developer of the past few years has grappled with. I'm definitely going to be checking this out.

Edit: seems like an easy improvement to this is add another field for raw transactions to check that the TX is valid and to inspect the script works as intended. I just noticed what you wrote about multi-sig but should be quite easy to code this (pybitcoin-lib already has all the code.)

[Kefkius]

First POST and OP congratulations because you just solved a problem that every Bitcoin developer of the past few years has grappled with. I'm definitely going to be checking this out.

Edit: seems like an easy improvement to this is add another field for raw transactions to check that the TX is valid and to inspect the script works as intended. I just noticed what you wrote about multi-sig but should be quite easy to code this (pybitcoin-lib already has all the code.)

Thanks! The thing about CHECKSIG is that the Stack View tool was getting pretty crowded so I didn't put in any way to include a transaction. But you're definitely right in that it wouldn't be very difficult to do. I think the best way to accomplish that is to create a tool called "Transaction Deserializer" or some such, and have it be able to interact with the Stack View tool. I'll give that a shot.

[Luke-Jr]

Would be nice if it could use libbitcoinconsensus for evaluation just to avoid any potential bugs.
I recall one time when Valgrind messed up an x86 instruction, it totally confused my debugging efforts for hours.
... and that was without money at stake ... :|

Disclosure: Shameless try-to-build-demand for reopening Bitcoin Core pull request #6178, "Refactor EvalScript into a CScriptExecution class, so single-stepping can be done"

[Uptrenda]

First POST and OP congratulations because you just solved a problem that every Bitcoin developer of the past few years has grappled with. I'm definitely going to be checking this out.

Edit: seems like an easy improvement to this is add another field for raw transactions to check that the TX is valid and to inspect the script works as intended. I just noticed what you wrote about multi-sig but should be quite easy to code this (pybitcoin-lib already has all the code.)

Thanks! The thing about CHECKSIG is that the Stack View tool was getting pretty crowded so I didn't put in any way to include a transaction. But you're definitely right in that it wouldn't be very difficult to do. I think the best way to accomplish that is to create a tool called "Transaction Deserializer" or some such, and have it be able to interact with the Stack View tool. I'll give that a shot.

Oh man, where were you 2 years ago when I was getting started? I'm wishing good things for this project 

[Kefkius]

Would be nice if it could use libbitcoinconsensus for evaluation just to avoid any potential bugs.
I recall one time when Valgrind messed up an x86 instruction, it totally confused my debugging efforts for hours.
... and that was without money at stake ... :|

Disclosure: Shameless try-to-build-demand for reopening Bitcoin Core pull request #6178, "Refactor EvalScript into a CScriptExecution class, so single-stepping can be done"

I hadn't thought of that. It's a good idea, albeit one that would complicate starting Hashmal (e.g. compiling the C++ extension). The current method of stepping through scripts - via re-implementing EvalScript() from python-bitcoinlib - is rather inelegant. I'm also relatively unfamiliar with C++ (as opposed to C) extensions in Python. Anyway, there probably should be a better implementation of script evaluation, so that's currently the only option on the table.

First POST and OP congratulations because you just solved a problem that every Bitcoin developer of the past few years has grappled with. I'm definitely going to be checking this out.

Edit: seems like an easy improvement to this is add another field for raw transactions to check that the TX is valid and to inspect the script works as intended. I just noticed what you wrote about multi-sig but should be quite easy to code this (pybitcoin-lib already has all the code.)

Thanks! The thing about CHECKSIG is that the Stack View tool was getting pretty crowded so I didn't put in any way to include a transaction. But you're definitely right in that it wouldn't be very difficult to do. I think the best way to accomplish that is to create a tool called "Transaction Deserializer" or some such, and have it be able to interact with the Stack View tool. I'll give that a shot.

Oh man, where were you 2 years ago when I was getting started? I'm wishing good things for this project 

Thanks for the good wishes.

[Luke-Jr]

Would be nice if it could use libbitcoinconsensus for evaluation just to avoid any potential bugs.
I recall one time when Valgrind messed up an x86 instruction, it totally confused my debugging efforts for hours.
... and that was without money at stake ... :|

Disclosure: Shameless try-to-build-demand for reopening Bitcoin Core pull request #6178, "Refactor EvalScript into a CScriptExecution class, so single-stepping can be done"

I hadn't thought of that. It's a good idea, albeit one that would complicate starting Hashmal (e.g. compiling the C++ extension). The current method of stepping through scripts - via re-implementing EvalScript() from python-bitcoinlib - is rather inelegant. I'm also relatively unfamiliar with C++ (as opposed to C) extensions in Python. Anyway, there probably should be a better implementation of script evaluation, so that's currently the only option on the table.

libbitcoinconsensus, while it does use C++, exports only a C API
Should be able to just use ctypes I would think (with stock libbitcoinconsensus lib).
(Of course, this only works with #6178 merged )

[sAt0sHiFanClub]

Well done, this looks really good. I think you are going in the right direction with this. 

[walletrecoveryservices]

Nice idea OP. Thanks for your contribution to the community.

[anton000]

Wow. Pretty awesome contribution op.

If this were only available 2 years go... Damn

[antanst]

Very nice, thank you!

Should there be a list of the Python dependencies somewhere, like a requirements file?

[SteamGamesBTC.com]

Python isn't so bad at all, Electrum is also written in Python and works. ;-) However the Windows version of Electrum is nicely compiled to the one executable file. Do you plan the same?

[Kefkius]

Very nice, thank you!

Should there be a list of the Python dependencies somewhere, like a requirements file?

Yeah, there's a requirements.txt now.

Python isn't so bad at all, Electrum is also written in Python and works. ;-) However the Windows version of Electrum is nicely compiled to the one executable file. Do you plan the same?

When it's a little more mature, definitely.

[CanaryInTheMine]

Great tool!! It's very useful, wish it was made sooner

[georgem]

exactly the tool I need right now. Thanks!

[Kefkius]

Thanks for the feedback. Repo transferred to its new home. We're now in #hashmal on freenode.

[mustyoshi]

Any chance of porting this to Javascript?

[Kefkius]

Any chance of porting this to Javascript?

Not really, no. The whole thing was designed with Python in mind.

Anyway, there are now some basic usage docs here. I've also put in a basic Transaction Deserializer tool which can be upgraded with the functionality talked about earlier in the thread at a later time.

The most significant update is that you can now specify a "spending transaction" in the Stack Evaluator, and select one of its inputs. That input's scriptSig will be pushed to the stack before your script starts. "OP_CHECKSIG" and "OP_CHECKSIGVERIFY" should work now.

Pretty soon I'll have to start incrementing the version number and providing changelogs.

[chrisrico]

I'm having difficulty getting it to run. Here's what I'm getting after installing from git on OSX Yosemite.

Code:

$ hashmal
Traceback (most recent call last):
  File "/usr/local/bin/hashmal", line 13, in <module>
    import hashmal_lib
  File "/usr/local/lib/python2.7/site-packages/hashmal_lib/__init__.py", line 5, in <module>
    from main_window import HashmalMain
  File "/usr/local/lib/python2.7/site-packages/hashmal_lib/main_window.py", line 8, in <module>
    from dock_handler import DockHandler
  File "/usr/local/lib/python2.7/site-packages/hashmal_lib/dock_handler.py", line 4, in <module>
    from docks.addr_encoder import AddrEncoder
  File "/usr/local/lib/python2.7/site-packages/hashmal_lib/docks/__init__.py", line 6, in <module>
    import tx_deserializer
ImportError: No module named tx_deserializer

[Kefkius]

I'm having difficulty getting it to run. Here's what I'm getting after installing from git on OSX Yosemite.

Code:

$ hashmal
Traceback (most recent call last):
  File "/usr/local/bin/hashmal", line 13, in <module>
    import hashmal_lib
  File "/usr/local/lib/python2.7/site-packages/hashmal_lib/__init__.py", line 5, in <module>
    from main_window import HashmalMain
  File "/usr/local/lib/python2.7/site-packages/hashmal_lib/main_window.py", line 8, in <module>
    from dock_handler import DockHandler
  File "/usr/local/lib/python2.7/site-packages/hashmal_lib/dock_handler.py", line 4, in <module>
    from docks.addr_encoder import AddrEncoder
  File "/usr/local/lib/python2.7/site-packages/hashmal_lib/docks/__init__.py", line 6, in <module>
    import tx_deserializer
ImportError: No module named tx_deserializer

My bad. I hadn't included that file in the list of modules in setup.py. Fixed now.