December 21, 2023

The Breakthrough Innovations Behind BEVM

Today, we will focus on BEVM from the technology that outstands other L2s.

We all know that there are already some excellent projects like Lightning network, Stacks, liquid network, RSK, RGB…

However, BEVM explores a unique approach compared to other solutions. We summarize some advantages compared to other L2s/Cross-chain Bridges, taking tBTC as an example.

Considering that this article is focused on technical features, we’ll try our best to convey it simply straightforward:)

BEVM has several key technical features that distinguish it from other L2 designs:

1. EVM Compatible

Fully works with existing Ethereum tools like MetaMask, Truffle, Hardhat, and Solidity language. This provides easy integration with the wider Ethereum ecosystem.

2. Use BTC as native gas

Uses native BTC for gas fees on BEVM, similar to how Layer 2s like Optimism use ETH as gas that leverages the scarcity and value security of Bitcoin.

3. Taproot Threshold Signature

It uses on-chain POS nodes to decentralize threshold signature verification. The Signal protocol is used to secure communication of the aggregated Schnorr signature pubkey/msg.

Taproot Threshold Signature is based on Musig2, which is a multi-signature protocol that completes signing in just two rounds of communication. Musig2 enhances the practicality compared to original Musig.

The nodes participating in multi-sig each generate key pairs, the first round exchanges keys, and the second round exchanges signature fragments. Once the signature fragments of all nodes are combined, a complete multi-party signature can be generated.

MuSig2 can support a large number of nodes to participate, realize a fair key aggregation mechanism, and generally improve the scalability and efficiency of multi-party signatures in the Bitcoin network.

This implementation fully reproduces the multi-signature scheme proposed in the Musig2 paper (version 20210706:150749). It provides versions for secp256k1 and sr25519, allowing use of Musig2 on Bitcoin and Polkadot.

The secp256k1 version aligns naming with the protocol and is compatible with the Schnorr signature in Bitcoin’s BIP340. This makes it applicable to Bitcoin.

The sr25519 version implements the Musig2 protocol on Ristretto compressed Ed25519 points.

4. Bitcoin Light Nodes

Uses Bitcoin light nodes on-chain that support Wasm to fetch data directly from the Bitcoin network. Avoids reliance on 3rd party data oracles.

5. Signal Privacy Protocol

Uses Signal protocol for private communication between nodes when doing threshold signatures. Prevents eavesdropping and data leaks.

6. ZK-STARK Ultra Light Nodes (upcoming)

ZK-STARKs, invented by StarkWare, enforce the integrity and privacy of computations on blockchains, using novel cryptographic proofs and modern algebra.

ZK-STARKs allow blockchains to move computations to a single off-chain STARK prover and then verify the integrity of those computations using an on-chain STARK Verifier.

After learning about our unique technologies, let’s look at why these technologies will bring more advantages than tBTC.

1.Use MuSig2 instead of sharding private keys to cunt down the risks.

Shamir’s Secret Sharing is a method of splitting the private key into multiple copies(n), which can realize the distributed storage of the private key.

As long as more than m shares are collected, the complete private key can be reconstructed. (m<n, ususlly=1/2 n)

However, once the secret keys are leaked or lost, it’s hard to deduce the original private key.

So, we come up with to use of MuSig2 to effectively cut down the risks.

2. All validators on Threshold Network are on-chain.

The validators of the Threshold Network are on-chain, it really increases trust and also avoids the opaque and easy-to-operate defects of the distributed network under the chain.

3. Use Bitcoin Light node to obtain data from BTC network.

If we use data oracle, a channel for data from off-chain transfer to the on-chain. There is a trust problem with Oracles: What if Oracles manipulate or tamper the data, or gather together off-chain, causing centralization risks?

Well, in our system, we use BTC light node on-chain, to grab data from Bitcoin network directly, avoiding trusting the third party(Oracles).

4. Use Signal protocol to realize the communication in BTC threshold Network.

Signal protocol is a secure communication protocol based on key-pair symmetric encryption and Perfect Forward Sophisticated to prevent eavesdropping on communication content.

Using Signal avoids the risks of data leakage, collusion, or external attacks when threshold signatures appear.

License: GPL v3