BACK-END MATCHING METHOD SUPPORTING FRONT-END KNOWLEDGE-BASED PROBABILISTIC AUTHENTICATION SYSTEMS FOR ENHANCED CREDENTIAL SECURITY

摘要

A party can authenticate itself by interacting with multiple servers without revealing the shared secret to any of the involved parties. The stored shared secret is strengthened and broken into shares and saved on the servers. The shared secret is safe against offline brute force attack unless all servers where the shares are stored are compromised. The compromise of any single server, or multiple servers—but less than the maximum number—will not allow the attacker to do a brute force analysis on the shared secret. This back end security enhancement is suitable for probabilistic front end authentication algorithms.

主权项

1. A method for knowledge-based probabilistic authentication of a client by server side resources, using a client identifier and a credential having a number of elements, where each element of the credential represents a parameter (e.g. a grid location) selected from a parameter set (the set of grid locations), the method comprising:
storing a data set for a given client identifier including a representation of the credential, in memory accessible by a first server in the server side resources, the representation including processed credential elements, the processed credential element for a particular credential element being results of a one-way function of the particular credential element and protected data, the protected data being protected from determination by the first server; storing a second data set including at least part of said protected data in memory accessible by a second server in the server side resources; receiving using the first server via data communications, a client identifier and an authentication response having a number of session values, where the each session value (e.g. characters selected from the grid) of the authentication response can be mapped to more than one parameter (grid locations) in the parameter set; transforming in server side resources, said session values of the authentication response into corresponding sets of intermediate values, each set in said sets of intermediate values having a member for each possible parameter (grid location) in the parameter set to which the corresponding session value of the response can be mapped, and sending said sets of intermediate values to the second server; generating a plurality of sets of possible processed credential element match values using the second server, each set of possible processed credential element match values of the authentication response based upon said one-way function of said protected data and a corresponding one of said sets of intermediate values, and sending said plurality of sets of possible processed credential element match values to the first server in an order different from an order in which the sets of intermediate values were received using the second server; using the first server, determining whether each of the sets of possible processed credential element match values includes one member that matches one of the processed credential elements in the representation of the credential; and if all of the sets of possible processed credential element match values for a given authentication response include one member that matches one of the processed credential elements in the representation of the credential, then signaling authentication success.