Xiaohui Liu

OP_PUSH_TX and its applications in Bitcoin smart contracts

What if a Bitcoin contract could inspect its own spending transaction? Discover how OP_PUSH_TX enables stateful applications previously deemed impossible, from on-chain games to financial instruments.

OP_PUSH_TX and its applications in Bitcoin smart contracts
#1about 2 minutes

Introduction to OP_PUSH_TX and its applications

An overview of the OP_PUSH_TX technique, its internal implementation, and the smart contract applications it enables, including a live demo.

#2about 1 minute

Introducing the OP_PUSH_TX technique for smart contracts

The OP_PUSH_TX technique allows a smart contract to access the current transaction's data by pushing it onto the stack.

#3about 1 minute

Accessing transaction data via the SIGHASH pre-image

The technique pushes the SIGHASH pre-image, which contains transaction data like inputs and outputs, onto the stack for inspection.

#4about 3 minutes

Implementing OP_PUSH_TX as a pseudo-opcode

The technique is implemented as a pseudo-opcode using existing script commands to verify the SIGHASH pre-image is for the current transaction.

#5about 5 minutes

Controlling future spending with transaction introspection

By inspecting the transaction pre-image, smart contracts can enforce rules on future outputs, replicating features like CLTV and P2SH.

#6about 3 minutes

Maintaining state across transactions with OP_PUSH_TX

Stateful smart contracts are created by dividing the locking script into immutable code and mutable data, ensuring state transitions correctly in subsequent transactions.

#7about 2 minutes

Building on-chain games and tokens with stateful contracts

The ability to maintain state enables complex applications like fully on-chain games, fungible and non-fungible tokens, and financial instruments.

#8about 2 minutes

Demonstrating a fully on-chain Tic-Tac-Toe game

A live demo shows a Tic-Tac-Toe game where each move is a Bitcoin transaction, enforcing game rules on-chain and preventing cheating.

#9about 2 minutes

Summary and resources for building with sCrypt

A recap of the OP_PUSH_TX technique and its applications, with links to sCrypt's open-source code, documentation, and community channels.

Related jobs
Jobs that call for the skills explored in this talk.

Matching moments

Crypto crime, EU regulation, and working while you sleep
01:15 MIN

Crypto crime, EU regulation, and working while you sleep

Fake or News: Self-Driving Cars on Subscription, Crypto Attacks Rising and Working While You Sleep - Théodore Lefèvre

Scripting presentations and demos in VS Code
14:14 MIN

Scripting presentations and demos in VS Code

Devs vs. Marketers, COBOL and Copilot, Make Live Coding Easy and more - The Best of LIVE 2025 - Part 3

Increasing the value of talk recordings post-event
04:57 MIN

Increasing the value of talk recordings post-event

Cat Herding with Lions and Tigers - Christian Heilmann

The value of progressive enhancement and semantic HTML
03:31 MIN

The value of progressive enhancement and semantic HTML

WeAreDevelopers LIVE – You Don’t Need JavaScript, Modern CSS and More

Playing a game of real or fake tech headlines
04:17 MIN

Playing a game of real or fake tech headlines

WeAreDevelopers LIVE – You Don’t Need JavaScript, Modern CSS and More

AI lawsuits, code flagging, and self-driving subscriptions
01:02 MIN

AI lawsuits, code flagging, and self-driving subscriptions

Fake or News: Self-Driving Cars on Subscription, Crypto Attacks Rising and Working While You Sleep - Théodore Lefèvre

Why you might not need JavaScript for everything
02:33 MIN

Why you might not need JavaScript for everything

WeAreDevelopers LIVE – You Don’t Need JavaScript, Modern CSS and More

Prompt injection as an unsolved AI security problem
07:39 MIN

Prompt injection as an unsolved AI security problem

AI in the Open and in Browsers - Tarek Ziadé

Featured Partners

Related Videos

See all videos
Bitcoin transactions- embedding and using data for applications built on Bitcoin SV33:37

Bitcoin transactions- embedding and using data for applications built on Bitcoin SV

Jack Davies & Alessio Pagani

Introduction to sCrypt - a smart contract language for Bitcoin SV47:45

Introduction to sCrypt - a smart contract language for Bitcoin SV

Liu Xiaohui

Nano services and dust return transactions + long chain 37:28

Nano services and dust return transactions + long chain

Matej Trampuš & Steve Shadders

Intermediate Bitcoin Script1:06:12

Intermediate Bitcoin Script

Steve Shadders

Introduction to TXT42:32

Introduction to TXT

Glenn Wolfe

Connect API for Bitcoin SV applications42:37

Connect API for Bitcoin SV applications

Rafa Jiménez

Business sensibilities when developing for Bitcoin46:29

Business sensibilities when developing for Bitcoin

Joshua Henslee

Bitcoin- Ledger vs Blockchain41:09

Bitcoin- Ledger vs Blockchain

Evan Freeman

Related Articles

View all articles
Build With Bitcoin SV
At Bitcoin Association, we work to advance business using the Bitcoin SV (BSV) blockchain. A rebirth of the original Bitcoin, Bitcoin SV has restored the protocol to the specifications of creator Satoshi Nakamoto, resulting in a public blockchain cap...
Build With Bitcoin SV

From learning to earning

Jobs that call for the skills explored in this talk.