Patent ID: 7577987

Claim:
A system for authentication of a client, comprising: a data processor including an interface to a database, an interface to a data network, and authentication system programs executable by the data processor, the database including records of client accounts, the record of a client account in the database holding client credentials, the client credentials including an account user name, client profile data and a shared-secret account authentication code comprising field contents arranged in an ordered set of data fields, the data fields in the ordered set having enumerated positions, and the field contents being arranged in the enumerated positions in accordance with a full pattern chosen by the client, and the system programs including, authentication logic supporting an authentication algorithm for authentication of a client based upon comparing client credentials including an account user name and an entry based on said account authentication code entered during an authentication session with client credentials stored in advance in the record of a client account, and system logic supporting client account administration for the authentication algorithm, the client account administration including at least one mode of operation that presents an interface to a client via the data network having at least a first tier of security requiring entry of one of the account user name and an email address, and a second tier of security, the system logic supporting the second tier including resources for generating an authentication challenge that identifies enumerated positions of a random subset of the ordered set of data fields, for receiving an authentication response from the client, for matching the authentication response with a part of the full pattern including the field contents from the random subset of the ordered set of data fields, and for making an authentication decision based on matching said part of the full pattern, wherein the random subset includes fewer data fields than all of the data fields in the ordered set.