The Sigma Book

Complete Technical Reference for SigmaState Interpreter, ErgoTrees, and Sigma Language

KYA: Know Your Assumptions

This is a PRE-ALPHA version. Before using this material:

1. Not Authoritative — This is NOT an official specification. It is a research/educational resource.
2. May Contain Errors — Content has not been formally verified.
3. Subject to Change — Chapters may be incomplete or substantially rewritten.
4. Verify Everything — Cross-reference against the source code.

Authoritative Sources:

• sigmastate-interpreter — Reference Scala implementation
• sigma-rust — Rust implementation
• ergo — Ergo node
• ErgoTree Spec (spec.pdf)

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A comprehensive technical reference for engineers who need deep understanding of the implementation details, algorithms, and design decisions behind the Ergo blockchain's smart contract system.

Contents

The book is organized into ten parts covering the full stack:

Part	Title	Chapters
I	Foundations	Introduction, Type System, ErgoTree Structure
II	Abstract Syntax Tree	Value Nodes, Operations & Opcodes, Methods on Types
III	Serialization	Serialization Framework, Value Serializers
IV	Cryptographic Foundations	Elliptic Curve Cryptography, Hash Functions, Sigma Protocols
V	Interpreter Engine	Evaluation Model, Cost Model, Verifier, Prover
VI	Compiler	ErgoScript Parser, Semantic Analysis, IR, Pipeline
VII	Data Structures	Collections, AVL+ Trees, Box Model
VIII	Ergo Node Integration	Interpreter Wrappers, Transaction Validation, Cost Limits, Wallet
IX	SDK and APIs	High-Level SDK, Key Derivation
X	Advanced Topics	Soft-Fork Mechanism, Cross-Platform, Performance

Plus comprehensive appendices covering type codes, opcodes, costs, methods, serialization formats, and version history.

Building the Book

Prerequisites

• Rust (for installing mdBook)
• mdBook

Install mdBook

cargo install mdbook

Build and Serve

# Build the book
mdbook build

# Serve locally with hot reload
mdbook serve --open

The built book will be in the book/ directory.

Source Material

This book is derived from:

• sigmastate-interpreter — Reference Scala implementation
• sigma-rust — Rust implementation
• ergo — Full node implementation
• ErgoTree Specification — Formal specification

Contributing

Contributions are welcome. Please open an issue or pull request on GitHub.

License

See LICENSE for details.