start abstract method
Begins a run.
initiator is the side that sends first. secret is the shared
low-entropy secret as raw bytes (the pairing code). initiatorId and
responderId are fixed role labels mixed into the transcript; both sides
must pass identical values.
Implementation
PakeSession start({
required bool initiator,
required List<int> secret,
List<int> initiatorId = const [],
List<int> responderId = const [],
});