personalSign(). See eth-sig-util for reference.
This document doesn't cover best practices for managing and storing keys due to a variety of methods different exchanges use to achieve a high level of security guarantees on their platform.
Depositterminology for an exchange has a different meaning from a deposit on the OMG Network. It's very important to distinguish between those two:
Vaultsmart contract on the Ethereum network. This creates a new deposit on the OMG Network and allows the depositor to transact on the network until a user decides to withdraw them back to Ethereum.
feeobject when constructing a transaction body with the OMG contract as follows: