A Lightweight, Cross-Platform Cryptocurrency Signing SDK Built with Golang

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The world of blockchain and digital wallets demands secure, efficient, and portable tools — especially for mobile environments where performance and size matter. Enter wallet-core, a compact and powerful Golang-based SDK designed to handle cryptocurrency transaction signing across platforms. Whether you're building a hot wallet, cold wallet, or multi-signature solution, this open-source library streamlines core cryptographic operations while maintaining flexibility and minimal footprint.

This guide explores the features, use cases, integration strategies, and optimization tips for wallet-core — a developer-first tool that empowers cross-platform wallet development without sacrificing security or scalability.

What Is wallet-core?

wallet-core is a lightweight, open-source cryptocurrency signing library written in Golang. Its primary function is to enable offline transaction signing, making it ideal for secure environments such as cold wallets. While it can operate online, its design prioritizes air-gapped security.

Built with gomobile, the SDK compiles into native binaries:

This allows seamless integration into native apps and cross-platform frameworks like React Native and Flutter, enabling consistent behavior across devices.

Currently supported cryptocurrencies include:

Support for additional blockchains is planned, ensuring future extensibility.

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Key Features

✅ BIP39 & BIP44 Support

Generate and restore wallets using standard mnemonic phrases (BIP39), and derive hierarchical deterministic keys across multiple cryptocurrencies using BIP44.

✅ Multi-Currency Transaction Handling

Build raw transactions and sign them securely:

✅ Cross-Platform Compatibility

Compile once, deploy everywhere:

✅ Modular Architecture

Only include what you need. The SDK supports granular builds:

✅ Small Binary Footprint

Optimized for mobile deployment:

Note: iOS framework sizes are still under evaluation (TBD).

What It Doesn’t Include (By Design)

To maintain focus on security and minimalism, wallet-core intentionally excludes:

This separation of concerns ensures that sensitive signing operations remain isolated from network exposure — a best practice in wallet architecture.

How to Use wallet-core

Developing a full-featured wallet requires combining wallet-core’s signing power with your own backend or node services.

Core Capabilities Provided by SDK:

You Must Implement:

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Documentation & Learning Resources

Comprehensive guides are available in the docs directory, covering:

Additionally:

Integration tests in the qa/ directory provide real-world usage examples, simulating complete wallet workflows.

Demo Projects

See wallet-core in action:

Frequently Asked Questions (FAQ)

Can I reduce the SDK size by including only specific modules?

Yes! Use the Makefile's build commands to export individual modules (e.g., only BTC or ETH). This modular approach lets you minimize app size based on required functionality.

How do I run tests?

Some tests spin up local chains for validation. Requirements vary:

Check the Makefile for integration test scripts.

Is there support for SegWit addresses?

No — current BTC implementation does not support Segregated Witness (SegWit) address signing. Only legacy Bitcoin address formats are supported.

Can I use this SDK alongside other gomobile-generated libraries?

Not easily. Due to Go's mobile toolchain limitations (golang/go#15956), linking multiple gomobile-built SDKs in one app can cause conflicts. Workarounds involve merging source code into a single build unit — though this hasn't been thoroughly tested.

Why avoid byte/int8 types when targeting iOS?

gomobile has known type restrictions when exporting to iOS. Using byte, int8, or uint8 may cause compilation issues. Prefer int64 or other compatible types for broader compatibility.

How should I handle architecture-specific builds?

For Android:

Gradle configurations also allow ABI filtering.

Contributing & Extending

wallet-core welcomes community input:

While formal commercial support isn't offered yet, enterprise inquiries can be sent to [email protected].

Known Limitations of gomobile

As gomobile is not widely adopted in production at scale, consider these constraints:

Always consult the official Go mobile issues page for updates.

Final Thoughts

wallet-core delivers a focused, secure, and modular approach to cryptocurrency transaction signing — perfect for developers building mobile-first wallets with Golang expertise. With strong support for BTC, ETH, Omni, and ERC20 tokens, plus seamless Android/iOS deployment via gomobile, it strikes a balance between functionality and minimalism.

Whether you're developing a cold storage solution or a multi-signature dApp interface, wallet-core gives you the foundation to build safely and efficiently.

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