Patent ID: 8406478

Claim:
A method of authenticating a user according to a biometric parameter of the user presented at an authentication device on a user-presented device on which is stored a biometric identification template divided into a secure portion and an open portion, the method comprising: transmitting to a client terminal data derived from said user biometric parameter at the authentication device; transmitting from a user-presented device to the client terminal only the open portion of the said biometric identification template held on the user-presented device, wherein the open portion is the portion containing data insufficient to construct a fake template that would allow an impostor to be incorrectly authenticated as a genuine user and comprises parameters of a predetermined number of unique features of the template; at the client terminal, implementing a first stage of a biometric identity authentication process between said derived data and said open portion to produce intermediate results, and transmitting the intermediate results of said biometric authentication process to the user-presented device, wherein said intermediate results comprise parameters for alignment of said derived data and said biometric identification template; at the user-presented device implementing a second stage of the biometric identity authentication process to complete the biometric identity authentication process using said intermediate results and said secure portion and issuing a biometric authentication result based thereon; and wherein the secure portion of the biometric identification template is the portion containing data unauthorized modification of which may cause an impostor to be incorrectly authenticated as a genuine user.