Creates a log that signs with a device identity, starting empty.
Appends a payload, signing it and chaining it onto the last entry.
StaticresumeCreates a log that carries on from the last entry an earlier one wrote.
This is what a device does after a restart: the chain continues at the next index and hashes onto the entry it left off at, so a reboot leaves no gap for a record to be removed through.
A log that signs what it is given and chains it onto what came before.