Biometric score normalizer

A method for normalizing biometric test scores generated by multiple biometric devices for multiple users, the method comprising the steps of:

• for each user enrolled to use each biometric device, maintaining a statistical database containing a standardized measure of accuracy for each possible score of the biometric device for this particular user;
• obtaining a current score from a biometric device for this particular user;
• and
• converting the current score to a standardized measure of accuracy obtained from the statistical database;
• wherein the step of maintaining a statistical database includes the following steps performed each time a user successfully accesses a protected system using a biometric device:
• obtaining current biometric data from this user;
• comparing the current biometric data of this user with stored biometric templates of other users enrolled to use the same biometric device, wherein the biometric data of this user are compared as “impostor data” with the other user templates, and a comparison score is obtained from the biometric device;
• after each comparing step, updating a count of impostor comparisons performed for each of the other users, and updating a count of the number of times the comparison score is obtained for impostor comparisons relative to each other user;
• updating the probability of occurrence of each comparison score;
• and
• computing an equivalent false acceptance rate from the probabilities of occurrence of the comparison scores, wherein the false acceptance rate provides an objective measure of security risk for this particular user and biometric device.

A biometric score normalizer for use in an authentication system having multiple biometric devices and multiple users, the biometric score normalizer comprising:

• a statistical database containing, for each user enrolled to use each biometric device, at least one standardized measure of accuracy for each possible score of the biometric device;
• means for accumulating data in the statistical database, wherein the at least one standardized measure of accuracy is updated each time a user successfully accesses the authentication system;
• and
• means for converting a raw biometric device score into at least one standardized measure of accuracy by accessing the statistical database.

A biometric score normalizer for use in an authentication system having multiple biometric devices and multiple users, the biometric score normalizer comprising:

• a statistical database containing, for each user enrolled to use each biometric device, at least one standardized measure of accuracy for each possible score of the biometric device;
• means for accumulating data in the statistical database, wherein the at least one standardized measure of accuracy is updated as users attempt access to the authentication system;
• and
• means for converting a raw biometric device score into at least one standardized measure of accuracy by accessing the statistical database;
• wherein the statistical database contains an equivalent value of false acceptance rate for each combination of user, biometric device and biometric device score, and the means for accumulating data in the statistical database includes:
• means for obtaining current biometric data from this user;
• means for comparing the current biometric data of this user with stored biometric templates of other users enrolled to use the same biometric device, wherein the biometric data of this user is compared as “impostor data” with the other user templates, and a comparison score Is obtained from the biometric device;
• means operative after the means for comparing, for updating a count of impostor comparisons performed for each of the other users, and updating a count of the number of times the comparison score is obtained for impostor comparisons relative to each other user;
• means for updating the probability of occurrence of each comparison score;
• and
• means for computing an equivalent false acceptance rate from the probabilities of occurrence of the comparison scores, wherein the false acceptance rate provides an objective measure of security risk for this particular user and biometric device.