Hop

Funds can be stolen if

1. Bonder submits invalid message bundle and is left unchallenged for 24 hours,
2. destination token contract is maliciously upgraded (CRITICAL).

Users can be censored if

3. AMB of the destination chain censors the message.

Principle of operation

Hop is a Liquidity Network with ability to facilitate fast transfers using Ethereum as a settlement layer. It uses a technical hToken and AMM between hToken and canonical token on a destination chain to facilitate token transfers. Users are isolated from individual risks related to destination chains.

Optimistic Validation with fallback to native bridge

Messages announcing token withdrawals are sent from the source to the destination chain using native AMB (Arbitrary Messaging Bridge) to Ethereum for a given chain source chain. Depending on a chain, these can be slow, e.g. 7-days for Optimistic Rollups. Designated actors called Bonders "pre-announce" the incoming transfer of a message bundle to the destination chain. For 24 hours anyone can challenge the validity of the message bundle. If left unchallenged, the bundle is assumed to be valid and Bonder can remove the collateral which make all withdrawals from this bundle to settle against bridge funds. If challenged, the Bonder's collateral is locked in a bridge until the native message arrives and challenge is resolved.

• Users can be censored if AMB of the destination chain censors the message.

• Funds can be stolen if Bonder submits invalid message bundle and is left unchallenged for 24 hours.

Destination tokens are upgradeable

Tokens transferred end up as "representation tokens" some of them may be upgradable.

• Funds can be stolen if destination token contract is maliciously upgraded (CRITICAL).