Security systems for protecting assets are described, including
password-based security systems that can provide different levels of
access responsive to entry of a primary or secondary password. In some
versions, user-configurable security rules can provide customized
responses to entry of primary or secondary passwords, including feigned
or limited access, security alerts, etc. Passwords comprising overt and
covert components can be used to provide enhanced security and improved
user control over system response. Improved security systems involving
transactions between multiple parties are also considered, with options
for user-customized security rules including primary and secondary
passwords, and reverse challenge and response methods. Systems for
Limited Use Credentials are also disclosed to reduce the risk of identity
theft.