bitcoin-script

Bitcoin scripts inline in Rust.

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Usage

This crate exports a script! macro which can be used to build Bitcoin scripts. The macro returns the Script type from the bitcoin crate.

Example:

#![feature(proc_macro_hygiene)]use bitcoin_script::bitcoin_script;let htlc_script = script!{OP_IFOP_SHA256 <digest> OP_EQUALVERIFYOP_DUPOP_SHA256 <seller_pubkey_hash>
OP_ELSE100OP_CSVOP_DROPOP_DUPOP_HASH160 <buyer_pubkey_hash>
OP_ENDIFOP_EQUALVERIFYOP_CHECKSIG};

Syntax

Scripts are based on the standard syntax made up of opcodes, base-10 integers, or hex string literals. Additionally, Rust expressions can be interpolated in order to support dynamically capturing Rust variables or computing values (delimited by <angle brackets> or {curly brackets}). The script! macro can be nested.

Whitespace is ignored - scripts can be formatted in the author's preferred style.

Opcodes

All normal opcodes are available, in the form OP_X.

let script = script!(OP_CHECKSIGOP_VERIFY);

Integer Literals

Positive and negative 64-bit integer literals can be used, and will resolve to their most efficient encoding.

For example:

• 2 will resolve to OP_PUSHNUM_2 (0x52)
• 255 will resolve to a length-delimited varint: 0x02ff00 (note the extra zero byte, due to the way Bitcoin scripts use the most-significant bit to represent the sign)`

let script = script!(123 -456999999);

Hex Literals

Hex strings can be specified, prefixed with 0x.

let script = script!(0x0102030405060708090a0b0c0d0e0fOP_HASH160);

Escape Sequences

Dynamic Rust expressions are supported inside the script, surrounded by angle brackets or in a code block. In many cases, this will just be a variable identifier, but this can also be a function call or arithmetic.

Rust expressions of the following types are supported:

• i64
• Vec<u8>
• bitcoin::PublicKey
• bitcoin::XOnlyPublicKey
• bitcoin::ScriptBuf

let bytes = vec![1,2,3];let script = script!{
<bytes> OP_CHECKSIGVERIFY
<2016*5> OP_CSV
<script! {OP_FALSEOP_TRUE}>
};

Optimality

Obsolete Opcodes are automatically removed when using the optimal_opcodes branch. E.g. a sequence of OP_0 OP_ROLL will be optimized away.