Bridging From Bitcoin

How to transfer assets between Bitcoin and Zulu: Pegging Mechanism and Atomic Swaps.

As a ZK Bitcoin solution, the Zulu system must facilitate the seamless transfer of assets between Bitcoin and Zulu.

Presently, all well-conceived cross-chain bridge designs incorporate the BitVM framework, exemplified by Robin's BitVM Bridge and ZK Base's ZKByte design. Zulu's cross-chain bridge for Bitcoin will be implemented utilizing the BitVM bridge, ensuring a trust-minimized security level.

The BitVM bridge can maintain a 1:1 ratio between the value of zBTC published on Zulu and the value of BTC locked on Bitcoin through a 2-way PEG mechanism. However, a challenge arises when crossing zBTC based on the BitVM bridge—its value remains fixed, equivalent to the value of BTC locked previously. Ordinarily, due to certain transaction behaviors, assets crossed back by regular users may not have a fixed value. To address this scenario, the system supports ordinary users in transferring assets between Bitcoin and Zulu through the mechanism of Atomic swaps. ZBTC crossed via the BitVM bridge can function as a liquidity provider for Atomic swaps in such situations.

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Peg IN/OUT Overview

Atomic Swaps Overview