Is it permissible for a husband to ask for his wife's phone or computer password if he suspects her involvement in illicit activities?

A believer should have a good opinion of fellow Muslims and avoid baseless doubts and negative suspicions, as Allah the Almighty says: (O you who have believed, avoid much [negative] assumption. Indeed, some assumption is sin. And do not spy). The general rule is that it is not permissible for a husband, under normal circumstances, to ask for his wife's phone or computer password, because this implies suspicion and accusation and may lead to the deterioration of the marital relationship. However, if there are signs or indications that the wife is committing Sharia violations, then there is no objection for him to ask her for the password, or even to use stratagems to ascertain the truth.