PIN recovery in a smart card

1. A method of controlling access to resources on a smart card, said method comprising:

providing a list of n questions for presentation to the user, where n is an integer;

receiving from the user answers to questions among the list of n questions;

determining how many of the received answers are correct; and

if a sufficient number of the n questions was answered correctly, granting access to the resources on the smart card;

wherein said sufficient number is equal to m, where m is an integer that is not greater than n;

further comprising:

causing the user to be prompted to enter a password as a condition for granting access to said resources on the smart card; and

receiving input from the user in response being prompted to enter the password, wherein providing the list of n questions is in response to receiving input from the user;

wherein the received input is an entered password, said method further comprising determining that the entered password is incorrect, and wherein providing for presentation to the user the list of n questions is in response to determining that the entered password is incorrect.

2. The method of claim 1 , wherein determining involves comparing the received answers to answers that are stored on the smart card.

3. The method of claim 2 , wherein comparing involves using a measure of closeness to determine whether that received answers are correct, wherein the measure of closeness identifies an entered answer to any selected one of the questions on the list of m questions as correct even though that entered answer is not identical to the corresponding answer stored on the smart card.

4. The method of claim 2 , wherein comparing the received answers to answers that are stored on the smart card comprises:

weighting a first set of the received answers such that a weight associated with the first set of received answers is greater than a weight associated with a second set of received answers;

comparing the received answers to answers that are stored on the smart card; and

calculating a cumulative score associated with the weight associated with the first set of received answers and the weight associated with the second set of received answers;

wherein if less than m of the cumulative score is correct, locking the smart card so that access to the resources on the smart card is blocked to the use.

5. The method of claim 1 , wherein if less than m of the received answers is correct, locking the smart card so that access to the resources on the smart card is blocked to the user.

6. The method of claim 1 , further comprising:

storing the list of n questions on the smart card; and

storing on the smart card a correct answer for each of the questions in the list of n questions.

7. The method of claim 6 , wherein storing the list of n questions on the smart card involves storing the list of n questions as a list of indices, each of which corresponds to a different one of the questions on the list of n questions.

8. The method of claim 6 , wherein storing the correct answer for each of the questions in the list of n questions involves storing the correct answers on the smart card in text form.

9. The method of claim 2 , wherein storing the correct answer for each of the questions in the list of n questions involves storing the correct answers on the smart card in a hashed form.

10. The method of claim 1 , wherein where m is less than n.

11. The method of claim 10 , wherein n equals 5.

12. The method of claim 10 , wherein m equals 3.

13. The method of claim 1 , wherein the received input instructs the smart card to bypass password entry.

14. The method of claim 1 , wherein receiving input from the user involves receiving from the user an incorrect password p times in succession, wherein p is an integer.

15. The method of claim 14 , wherein p is equal to 3.

16. The method of claim 1 , further comprising storing a password in the smart card, wherein granting access to the resources on the smart card involves sending the stored password to another module implemented on the smart card that is responsible for granting and denying access to the resources on the smart card.

17. A smart card comprising:

a microprocessor;

an interface through which the smart card interfaces with a card reader; and

memory storing a password for enabling a user to gain access to resources on the smart card, a list of n questions along with answers thereto, and code which when executed on the microprocessor causes the microprocessor to:

provide a list of n questions for presentation to the user, where n is an integer;

receive from the user answers to questions among the list of n questions;

determine how many of the received answers are correct; and

if a sufficient number of the n questions was answered correctly, grant access to the resources on the smart card;

wherein said sufficient number is equal to m, where m is an integer that is not greater than n;

wherein the code further causes the microprocessor to:

cause the user to be prompted to enter the password as a condition for granting access to said resources on the smart card;

accent input from the user in response to being prompted to enter the password; and

based on the received input from the user, provide the list of n questions for presentation to the user;

wherein the received input is an entered password, wherein said code further causes the microprocessor to determine that the entered password is incorrect, and wherein said code causes the microprocessor to provide for presentation to the user the list of n questions in response to determining that the entered password is incorrect.

18. The smart card of claim 17 , wherein said code causes the microprocessor to determine how many of the received answers are correct by comparing the received answers to answers that are stored on the smart card.

19. The smart card of claim 17 , wherein said code causes the microprocessor to place the smart card in a locked state if less than m of the received answers is correct, wherein the locked state blocks the user from gaining access to the resources on the smart card.

20. The smart card of claim 17 , wherein the list of n questions is stored as a list of indices, each of which corresponds to a different one of the questions on the list of n questions.

21. The smart card of claim 17 , wherein the correct answer for each of the questions in the list of n questions is stored in text form.

22. The smart card of claim 17 , wherein the correct answer for each of the questions in the list of n questions is stored in a hashed form.

23. The smart card of claim 17 , wherein the code causes the microprocessor to compare the received answers to answers that are stored on the smart card by using a measure of closeness to determine whether that received answers are correct, wherein the measure of closeness identifies an entered answer to any selected one of the questions on the list of m questions as correct even though that entered answer is not identical to the corresponding answer stored on the smart card.

24. The smart card of claim 17 , wherein m is less than n.

25. The smart card of claim 24 , wherein n equals 5.

26. The smart card of claim 17 , wherein m equals 3.

27. The smart card of claim 17 , wherein the received input instructs the smart card to bypass password entry.

28. The smart card of claim 17 , wherein when determining how many of the received answers are correct by comparing the received answers to answers that are stored on the smart card, the smart card is configured to:

weight a first set of the received answers such that a weight associated with the first set of received answers is greater than a weight associated with a second set of received answers;

compare the received answers to answers that are stored on the smart card; and

calculate a cumulative score associated with the weight associated with the first set of received answers and the weight associated with the second set of received answers;

wherein if less than m of the cumulative score is correct, the smart card is configured to lock the smart card so that access to the resources on the smart card is blocked to the use.