ChainX X-BTC2.0 —Vault trusteeship scheme

2 min readMar 17, 2021

X-BTC 2.0 is a trustless and highly efficient inter-chain asset system based on the XCLAIM framework through which two protocols are introduced to enable distributive, transparent, consistent, and anticensorship cross-region blockchain transactions. The most prominent difference from X-BTC 1.0 is the Vault (asset custodian) mechanism which allows more people to engage in assets’ chain crossing.

X-BTC 2.0 Vault advantages

XCLAIM overcomes the limitations of centralization in the following ways

Security auditing log

Build a log to record all users’ behavior on Bitcoin and ChainX

Proof of transaction inclusion

Relay is used to prove to ChainX the correct behavior on Bitcoin

Proof or punishment

XCLAIM does not rely on last-minute fraud-proof (which renders the system passive) but requires proactive proof of correct behavior.

Excessive collateral

Untrusted Vaults, subjected to collateral (PCX), have to establish a mechanism to mitigate exchange rate fluctuations

X-BTC 2.0 Vault scheme process

1)Vault locks collateral on the ChainX chain;

2)Users transfer Bitcoins to Vault for locking;

3)Submit lock proof to ChainX;

4)ChainX smart contract locks the amount in Vault and issues XBTC to the user’s account.

Inter-chain withdrawal

1)Users burn X-BTC through ChainX smart contract;

2)Vault transfers Bitcoins to the user after witnessing the unlock event;

3)Vault submits the released proof to ChainX to unlock the collateral.

About ChainX




ChainX is a BTC Layer 2 solution compatible with EVM that utilizes Bitcoin as a gas fee, serving as the predecessor network of BEVM.