Method of data caching on a smartcard

• US 20040034734A1
• Filed: 08/13/2002
• Published: 02/19/2004
• Est. Priority Date: 08/13/2002
• Status: Active Grant

• Current Assignee: Assa Abloy AB
• Original Assignee: ActivCard, Inc. (Assa Abloy AB)
• Inventors: Boyer, John
• Granted Patent: US 6,880,037 B2
• Time in Patent Office: Days
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0804 with main memory updating G06F12/0806 takes precedence
• CPC Class Codes: G06F 12/0868 Data transfer between cache memory and other subsystems, e.g. storage devices or host systems
• CPC Class Codes: G06F 2212/177 Smart card

Abstract

Smartcards are gaining acceptance as a secure medium for storing information, typically of a personal and confidential nature. Unfortunately, the process of storing information to the smartcard is a time consuming task, often taking much longer than to read the same amount of information from the card. The non-volatile memory within the smartcard is typically of the FLASH type and does not facilitate fast writing a fast writing process thereto. In order to speed up this process, a comparative writing algorithm is utilized which only writes changed data to the smartcard memory, thus eliminating the need for storing duplicate information.

Claims

1. A method of storing changed information within a non-volatile memory of a smartcard comprising the steps of:

caching data from within the smartcard, the cached data stored in a location in memory other than memory within the smartcard;

providing data for storage within the smartcard;

comparing the provided data for storage to at least a portion of the cached data retrieved one of directly and indirectly from the location to determine a data portion thereof less than the whole and having therein changed data; and

writing the determined data portion less than the whole to the smartcard.

2. A method of storing changed information according to claim 1, wherein the step of writing comprises the steps of:

executing a write command for writing data consisting of the data portion less than the whole to the smartcard.

3. A method of storing changed information according to claim 1, wherein the step of comparing is performed for determining at least a varied range of data having differences therebetween, and wherein the portion of the data less than the whole includes the at least a varied range.

4. A method according to claim 3, comprising the step of determining a distance between two varied ranges of the at least a varied range within the data for storage and when the distance is less than a distance of N units, including the data between the two varied ranges and the two varied ranges as a single varied range.

5. A method according to claim 4, wherein each determined varied range is written to the smartcard with a different write operation.

6. A method according to claim 3, wherein each determined varied range is written to the smartcard with a different write operation.

7. A method of storing changed information according to claim 1, wherein the portion is a byte.

8. A method of storing changed information according to claim 1, wherein the portion is data from a first changed byte to a last changed byte and excluding some of the data at least one of before the first changed byte and after the last changed byte.

9. A method of storing changed information according to claim 8, wherein the step of writing comprises the steps of:

executing a write command for writing data consisting of the data from a first changed byte to a last changed byte.

10. A method of storing changed information according to claim 1, wherein the compared data portion is a smallest writable data unit and wherein when two portions are other than identical and are spaced apart less than a distance of N smallest writable data units, the two portions and data therebetween are stored as the determined portion.

11. A method according to claim 10, wherein a time to write a unit of data to the smartcard is T1 and a time to set up a write operation is T2 and wherein (N)(T1)>

=T2.

12. A method of storing changed information according to claim 10, wherein the step of writing comprises the steps of:

executing a write command for writing data consisting of the data stored as the determined portion.

13. A method of storing changed information according to claim 7, wherein the provided data is derived from the cached data.

14. A method of storing changed information according to claim 13, wherein the provided data is stored in cache memory at a different location than the cached data prior to writing thereof to the smartcard.

15. A method of storing changed information according to claim 1, wherein the step of comparing data is performed by a processor.

16. An apparatus for storing changed information within a non-volatile memory of a smartcard comprising:

a memory having a first and a second memory locations and other than within a smartcard;

a processor for reading data from the smartcard memory, for storing the read data into the first memory location, for copying a portion of the data from the first memory location and storing modified data in the second memory location, and for comparing the data stored within the first memory location to the data stored within the second memory location and storing within the smartcard memory at least a portion of the modified data that is different, the at least a portion being less than the whole of the read data.

17. An apparatus for storing changed information according to claim 16, wherein the compared data is a smallest writable data unit.

18. An apparatus for storing changed information according to claim 17, wherein the smallest writable data unit is a byte.

19. A storage medium having stored thereon data indicative of a plurality of instructions for performing the steps of:

caching data from within a smartcard, the cached data stored in a location in memory other than memory within the smartcard;

providing data for storage within the smartcard at locations from which the cached data was retrieved;

comparing the provided data for storage to at least a portion of the cached data retrieved one of directly and indirectly from the location to determine a data portion less than the whole and having therein changed data; and

writing the determined data portion to the smartcard.

20. A storage medium according to claim 19, wherein the data relating to the step of writing is indicative of writing data consisting of the data portion less than the whole to the smartcard.

21. A storage medium according to claim 19, wherein the data indicative of the step of comparing is indicative of determining at least a varied range of data having differences therebetween, and wherein the portion of the data less than the whole includes the at least a varied range.

22. A storage medium according to claim 21, comprising data stored within the storage medium and relating to the step of determining a distance between two varied ranges of the at least a varied range within the data for storage and when the distance is less than a distance of N units, including the data between the two varied ranges and the two varied ranges as a single varied range.

23. A storage medium according to claim 22, wherein the data relating to instructions is relating to instructions that when performed result in each determined varied range being written to the smartcard with a different write operation.

24. A storage medium according to claim 21, wherein the data relating to instructions is relating to instructions that when performed result in each determined varied range being written to the smartcard with a different write operation.

25. A storage medium of storing changed information according to claim 19, wherein the portion is a byte.

26. A storage medium of storing changed information according to claim 19, wherein the data relating to instructions is relating to instructions that when performed result in the portion being data from a first changed byte to a last changed byte and excluding some of the data at least one of before the first changed byte and after the last changed byte.

27. A storage medium of storing changed information according to claim 26, wherein the data relating to the step of writing is indicative of steps of:

executing a write command for writing data consisting of the data from a first changed byte to a last changed byte.

28. A storage medium of storing changed information according to claim 19, wherein the data relating to instructions is relating to instructions that when performed result in the compared data portion being a multiple of a smallest writable data unit and when two portions are other than identical and are spaced apart less than a distance of N smallest writable data units, the two portions and data therebetween are stored as the determined portion.

29. A storage medium according to claim 28, wherein a time to write a unit of data to the smartcard is T1 and a time to set up a write operation is T2 and wherein (N)(T1)>

=T2.

30. A storage medium according to claim 28, wherein the data relating to the step of writing comprises the data relating to step of:

executing a write command for writing data consisting of the data stored as the determined portion.