A system for analyzing and modifying passwords in a manner that provides a user with a strong and usable/memorable password. The user would propose a password that has relevance and can be remembered. The invention would evaluate the password to ascertain its strength. The evaluation is based on a probabilistic password cracking system that is trained on sets of revealed passwords and that can generate password guesses in highest probability order. If the user's proposed password is strong enough, the proposed password is accepted. If the user's proposed password is not strong enough, the system will reject it. If the proposed password is rejected, the system modifies the password and suggests one or more stronger passwords. The modified passwords would have limited modifications to the proposed password. Thus, the user has a tested strong and memorable password.