Patent ID: 9537658
Date: 2017-01-03
CPC Classifications: G06F,H04L

Claim:
1. A system comprising: an access control server configured to communicate with user computers via a network and control access by the user computers to a resource in dependence on authentication of user passwords associated with respective user IDs; and a plurality n of authentication servers configured to store respective secret values and communicate with the access control server via the network; wherein the access control server is further configured to store, for each said user ID, a first ciphertext produced by encrypting a user password associated with a user ID using a predetermined algorithm dependent on said secret values; and wherein, in response to receipt from a user computer of a received user ID and an input password, the access control server is further configured to communicate with a plurality k≦n of authentication servers to implement a password authentication protocol, including use by the plurality k of authentication servers of the respective secret values, in which a second ciphertext is produced by encrypting the input password using said predetermined algorithm, and the access control server is further configured to use the first and second ciphertexts to determine whether the input password equals the user password for the received user ID to permit access to the resource by the user computer.