There are various different payloads that are signed off-chain by a user or a whitelisted operator account and are verified on-chain. All payloads are expected to be signed using signPersonalMessage(message: Uint8Array). The method performs following operations on the input message bytes before signing is:

Sui typescript SDK as well as on-chain move language provides support for creating and validating signatures using signPersonalMessage()

On Pro, the following eight payloads are signed off-chain and verified on-chain as part of different contract calls: