The Next Chain Fusion Milestone enters Test Phase as Threshold-Schnorr Test Key is Rolled Out

Chain Fusion enables interoperability across blockchains via network integrations and threshold signing. Today we announce the launch of the test phase for the Deuterium Milestone, the next step in the Chain Fusion roadmap for ICP. The first phase of this milestone is to roll out a threshold-Schnorr signing key, enabling developers and projects to begin their testing and integration processes.

The Chain Fusion Roadmap

The Chain Fusion roadmap is designed to progressively enhance the cross-chain capabilities of ICP, making it the go-to network for building multichain dapps and services. The Chain Fusion journey started by rolling out threshold-ECDSA signing which allowed smart contracts to sign Bitcoin and Ethereum transactions. A direct network integration with Bitcoin allowed smart contracts to read and write Bitcoin state directly from ICP. The recent Tritium Milestone saw the release of the decentralized RPC integration for Ethereum and EVM chains. Check out the full list of supported chains here.

The next milestone on the Chain Fusion Roadmap is Deuterium.

The Deuterium Milestone

The Deuterium Milestone comprises two key features:

Threshold-Schnorr signing

Schnorr-like digital signatures are popular in blockchains as they are simple in design, efficient, and allow for easier aggregate signatures, multi-signatures and threshold signatures. Enabling the support for threshold-Schnorr on ICP can enable canisters to sign taproot transactions and to host a broader range of crypto assets. The variant of Schnorr implemented in this milestone is BIP340: this is the variant used in Bitcoin, and also used in ordinals like BRC-20.

On-chain Bitcoin block headers

Currently ICP maintains only the UTXO set of Bitcoin. This feature will see ICP additionally maintaining Bitcoin block headers. This will allow smart contracts to access the full content of a Bitcoin block which is becoming increasingly relevant as new metaprotocols tend to write data to the block header.

We are currently in the test phase of the Deuterium Milestone. In this initial phase, the test key for Schnorr-BIP340 has been generated on an application subnet. Once this phase is complete, we can propose a production key on the fiduciary subnet and officially release it as part of the Deuterium milestone.

It’s important to note that this key should be used for testing purposes only and not to store any major value, as testing and security reviews are in progress.

The Benefits of Schnorr

Schnorr signatures unlock several interesting multichain features and initiatives. They enable support for Bitcoin taproot transactions on ICP, facilitating Bitcoin inscriptions and fungible tokens like BRC-20. These capabilities are important for enhancing multichain wallets and creating more “twin” ck-tokens on ICP, like ckBRC20. Additionally, Schnorr signatures enable direct integrations with other chains, thereby boosting efficiency with higher signature throughput and lower fees compared to tECDSA. Future iterations could leverage Schnorr-specific techniques for further efficiency gains.

Schnorr is also widely used across the internet, allowing canisters to sign x.509 certificates and act as decentralized Certificate Authorities. Moreover, it supports GPG signing for software distribution, forming the basis of decentralized repositories.

Ecosystem plans for Threshold-Schnorr

Several projects in the Bitcoin and ICP ecosystems are already planning to leverage threshold Schnorr (tSchnorr) for a host of innovative solutions:

• Bitomni: Bitomni’s BitoBridge, a pioneering Bitcoin omnichain bridge, plans to use tSchnorr signatures to extend Bitcoin support and facilitate the integration of BRC20 tokens.
• AstroX: AstroX will use tSchnorr for bridging assets seamlessly and as a keyless multisig wallet solution, enhancing security and ease of use.
• Helix: With the introduction of the tSchnorr Canister, Helix Markets users will be able to trade their favorite ICP and tokens from various ecosystems effortlessly. This feature eliminates the need for bridging or wrapping tokens, offering a streamlined and efficient trading experience on one platform.
• Omnity: tSchnorr will become Omnity’s rocket engine, enabling the handling of Bitcoin Taproot assets.
• Bioniq: Bioniq will use tSchnorr for multiple applications, ensuring enhanced security and performance across their platform.

Want to start using tSchnorr?

Resources Available:

• The developer documentation
• Threshold-Schnorr examples in Motoko and Rust
• Taproot transaction Demo Code
• Inscriptions example
• Questions, comments, feedback and discussion are very welcome in the Forum

We encourage all interested developers to participate in this test phase and provide feedback to help us gain confidence for the release of the production key, and we’re super excited to see your projects.

Upcoming Production Key Release

Following feedback and security reviews, the release of the production key is expected to occur in the coming weeks. This, coupled with the release of the on-chain Bitcoin headers will mark the final step and completion of the Deuterium Milestone.

Stay tuned for more updates as we approach the release of the production key. Follow us on X and Medium for the latest news and announcements.

Read more about ICP as a Bitcoin L2 — https://internetcomputer.org/bitcoin-integration