When using external signing in Canton 3.3, is there a time limit between when I prepare and sign the transaction with an external key and when I submit it?
For example, can I sign a transaction today using an external key for submission at an unspecified future date? (assuming any contracts I reference are still active at the time of submission)
The time limit depends on the synchronizer. On MainNet it is 24h which is also the default in Canton.
Note that the limitation on contracts still needing to be active matters for Canton Coin in particular as well as transactions there usually reference an OpenMiningRound contract which is only active for ~20min.
Furthermore, if one of the choice exercised uses getTime, then the maximal time between preparation and submission is bounded by the ledger_time_record_time_tolerance (proto), which is set to 1 minute on MainNet.
Canton 3.3 provides new primitives for avoiding getTime in common cases as explained here: How To Implement Time Constraints — Digital Asset’s platform documentation