hard20 pts · first answer countslayer-2smart-contract-security

Trusting a cross-chain message

An L2 contract mints tokens when it receives a message from a bridge messenger. It checks msg.sender == messenger. What else must it check?

A.Nothing, the messenger check is enoughB.That the original sender on the source chain (for example via messenger.xDomainMessageSender()) is the trusted L1 contractC.That tx.origin is the bridgeD.That the message arrived within one block

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