Rust for Bitcoiners
  • About this repo
  • Why Current Rust resources are not enough?
  • Rust for Bitcoiners: Project-Oriented Course Outline
  • bitcoin_in_rust
    • Understanding bitcoin blockchain structure and storage capabilities
    • ch1
      • design
    • ch2
      • What is mining?
      • segwit
    • ch0
      • core_lib
        • hashing
  • bitdevs
    • playgrounds
  • Preface
    • archives
      • Introduction to the Clap crate
      • one_way_functions_examples
    • module_1
      • Immutable by default
      • How to represent numbers in Rust?
      • Introduction to Pointers
      • Arrays and Slices in rust
      • Function
      • Loops in Rust
      • Can you see why Rust is best fit for Bitcoin related applications?
    • module_2
      • Data Types
      • Enums
      • Method call syntax
      • Summary
    • module_3
      • What is Box?
      • 2_syntax_sugar_and_traits
      • Linked List in Rust
    • module_4
      • Developing Software for bitcoin
      • User Interaction in Rust through command line
      • Option and Result
      • Interacting with Bitcoin node using RPC
    • module_5
      • Traits
      • Parsing json data with serde
      • Overview of bitcoin crate
    • module_6
      • What is Rc?
      • When Unique mutable borrow rule is too restrictive
      • Deref Coercion
      • memory_model
        • 0_marker_traits
    • module_7
      • Multi-tasking Computers
      • How to cordinate multiple threads
      • Counting the total number of bitcoin transactions
  • rust-for-bitcoiners-2
    • office_hour_1
    • Course plan
    • assignments
      • Implement your own hashing algorithm
        • rust_hashing_code_detailed
      • a-5
      • Assignment 6
      • Bitcoin Protocol Development - Week 8: Connecting to P2P network
        • Tips on writing with rust
  • Course Outline
    • assignments
      • Bitcoin scripting Arithmetic using Rust
  • tutorials
    • Observing the fee trends using Rust
    • Privacy concerns of a Transaction and it's implication in Coinselection
    • Building_UTXO_Set
    • JSON_serialization_with_serde
    • de_se_rialization
      • Hex encoding
      • rust-bitcoin-crate
        • Private Key using bitcoin crate
  • c_and_rust
    • day1
      • day1
    • day2
      • Lifetimes in Rust
    • day3
      • Owning references vs Borrowing References
  • rust-for-bitcoiners-1
    • day1
      • Day1 plan
    • day2
      • Day2 plan
      • Summary of 2nd Lecture
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  • What is the syntax of Bitcoin scripting?
  • How to represent Scripts in Rust?
  • Assignment task
  1. Course Outline
  2. assignments

Bitcoin scripting Arithmetic using Rust

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Last updated 7 months ago

Scripting is the programming language used in bitcoin to validate the ownership of bitcoins and validation of a transaction.

Using scripts we define the contract which has to be fulfilled.

The contract is a program, if the correct inputs are provided it will evaluate to true.

For this assignment we will be using Bitcoin scripting semantics to evaluate integer arithmetic expressions. This I believe is a better way to teach about scripting rather than directly jumping into complicated payment contracts. Because everyone understands addition and subtraction 😉.

What is the syntax of Bitcoin scripting?

It is precise to think of bitcoin scripting language as an assembly language. It has a set of commands which has a corresponding opcode(a byte). The input data are part of the Script as well. A script can have any other arbitrary data as well.

Review document for thorough overview of script op codes.

How to represent Scripts in Rust?

We need a type which identifies various op codes, there are PUSH opcodes to include arbitrary fixed sized data in scripts. Scripts are evaluated word by word using a stack to store intermediate results.

For example consider this simple script [OP_1, OPP_1ADD, OPP_1ADD]. While reading the first opcode, number 1 is pushed into the stack [1]. The second opcode increments 1 to the top element of the stack resulting in [2], similarly after the last one we have [3] as the stack state.

It is this simple, actually Assembly language is also very simplistic in design and easy to understand. The problem is that it is very tedious to write complicated logic with this simple design.

But as a programmer it is very easy to write a function to evaluate the scripts and that is exactly what you are going to do in this assignment.

Assignment task

Complete the functions and types as specified in the main.rs file. The goal is to pass all the tests. You are expected to handle opcodes related to Arithmetic, FLOW CONTROL, CONSTANTS and STACK only. Not all of them are necessary.

BONUS: You are free to include logic to evaluate additional opcodes and complicated scripts. But make sure to test them too!

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