Method and smart card adapted for progressive fingerprint enrollment

A smart card comprising a fingerprint sensing system including a fingerprint sensor configured for capturing a fingerprint representation of a fingerprint pattern of a finger of a user, a wireless transceiver for wireless communication with an electronic transaction terminal, and processing circuitry connected to and configured to control the operation of the fingerprint sensor, wherein the smart card is adapted for transition between a fingerprint authentication inactive state and a fingerprint authentication active state, wherein the processing circuitry is adapted to:

• acquire, using the fingerprint sensor, a partial fingerprint representation of a portion of the user's fingerprint during a present step in the multi-step fingerprint authentication activation;
• extract fingerprint features from the partial fingerprint representation, forming a present set of fingerprint features;
• determine a similarity level between the present set of extracted fingerprint features and sets of previously extracted fingerprint features, wherein the sets of previously extracted fingerprint features are formed during a preceding step in the multi-step fingerprint authentication activation;
• form a combined set of extracted fingerprint features if the similarity level is above a first threshold;
• complete, if an enrollment criterion is met, the multi-step fingerprint authentication activation by forming a fingerprint template based on the combined set of extracted fingerprint features;
• request the user to input a PIN code in the electronic transaction terminal;
• authenticate the PIN code;
• and
• save the fingerprint template together with an identifier for the fingerprint to thereby enroll the fingerprint of the user's finger only if the PIN code has been successfully authenticated.

A computer program product comprising a non-transitory computer readable medium having stored thereon computer program means for multi-step activation of fingerprint authentication for a user of a smart card, the smart card comprising a fingerprint sensing system including a fingerprint sensor configured for capturing a fingerprint representation of a fingerprint pattern of a finger of a user, a wireless transceiver for wireless communication with an electronic transaction terminal, and processing circuitry connected to and configured to control the operation of the fingerprint sensor, the computer program product comprising:

• code for acquiring, using the fingerprint sensor, a partial fingerprint representation of a portion of the user's fingerprint during a present step in the multi-step fingerprint authentication activation;
• code for extracting, using the processing circuitry, fingerprint features from the partial fingerprint representation, forming a present set of fingerprint features;
• code for determining, using the processing circuitry, a similarity level between the present set of extracted fingerprint features and sets of previously extracted fingerprint features, wherein the sets of previously extracted fingerprint features are formed during a preceding step in the multi-step fingerprint authentication activation;
• code for forming, using the processing circuitry, a combined set of extracted fingerprint features if the similarity level is above a first threshold;
• code for completing, if an enrollment criterion is met, the multi-step fingerprint authentication activation by forming a fingerprint template based on the combined set of extracted fingerprint features;
• code for requesting the user to input a PIN code in the electronic transaction terminal;
• code for authenticating the PIN code;
• and
• code for saving the fingerprint template together with an identifier for the fingerprint to thereby enroll the fingerprint of the user's finger only if the PIN code has been successfully authenticated.

A method of multi-step activation of fingerprint authentication for a user of a smart card, the smart card comprising a fingerprint sensing system including a fingerprint sensor configured for capturing a fingerprint representation of a fingerprint pattern of a finger of a user, a wireless transceiver for wireless communication with an electronic transaction terminal and processing circuitry connected to and configured to control the operation of the fingerprint sensor, the method comprising:

• requesting the user to input a PIN code in the electronic transaction terminal;
• authenticating the PIN code;
• acquiring, using the fingerprint sensor, only if the PIN code has been successfully authenticated, a partial fingerprint representation of a portion of the user's fingerprint during a present step in the multi-step fingerprint authentication activation;
• extracting, using the processing circuitry, fingerprint features from the partial fingerprint representation, forming a present set of fingerprint features;
• determining, using the processing circuitry, a similarity level between the present set of extracted fingerprint features and sets of previously extracted fingerprint features, wherein the sets of previously extracted fingerprint features are formed during a preceding step in the multi-step fingerprint authentication activation;
• forming, using the processing circuitry, a combined set of extracted fingerprint features if the similarity level is above a first threshold;
• completing, if an enrollment criterion is met, the multi-step fingerprint authentication activation by forming a fingerprint template based on the combined set of extracted fingerprint features;
• saving the fingerprint template together with an identifier for the fingerprint to thereby enroll the fingerprint of the user's finger, and
• enabling fingerprint authentication for the user of the smart card.