METHOD FOR SECURELY STORING DATA IN A MEMORY OF A PORTABLE DATA CARRIER

• US 20110225383A1
• Filed: 08/20/2009
• Published: 09/15/2011
• Est. Priority Date: 11/17/2008
• Status: Active Grant

• Current Assignee: Giesecke + Devrient Mobile Security GmBH (Giesecke & Devrient GmbH)
• Original Assignee: Giesecke & Devrient GmbH
• Inventors: Rankl, Wolfgang
• Granted Patent: US 8,838,925 B2
• Time in Patent Office: Days
• US Class Current: 711/163
• CPC Class Codes: G06F 21/79 in semiconductor storage media, e.g. directly-addressable memories

Abstract

A method for securely storing data in a multilevel memory of a portable data carrier. The multilevel memory includes one or several multilevel memory cells (SZ) which can assume respectively at least three levels (E, NE). The at least three levels represent a different data content, regarding which respective levels (E, NE) of a memory cell (SZ) are defined as valid or invalid. The levels (E, NE) of a respective memory cell (SZ) are selectively defined as valid or invalid in dependence on a required security level.

Claims

1-9. -9. (canceled)

10. A method for securely storing data in a multilevel memory of a portable data carrier, with the multilevel memory comprising one or several multilevel memory cells which can respectively assume at least three levels representing a different data content, in which respective levels of a memory cell are defined as valid or invalid, comprising:

selectively defining the levels of a respective memory cell as valid or invalid in dependence on a required security level.

11. The method according to claim 10, including varying the ratio of the number of valid to invalid levels of a respective memory cell in dependence on the required security level.

12. The method according to claim 10, including providing the memory cell on a maximally required security level with only one valid level.

13. The method according to claim 10, including defining, on a minimally required security level, all levels of the memory cell as valid.

14. The method according to claim 10, including dynamically or within the framework of production defining valid and invalid levels for the one or the several memory cells of the multilevel memory.

15. The method according to claim 14, wherein the dynamic definition of valid and invalid levels for the one or the several memory cells is carried out using a table, a function or a pseudo-random number generator, whose output is deterministic.

16. The method according to claim 15, wherein during the reading of data from a memory cell the permissible levels are determined for the memory cell concerned via the table, the function or the pseudo-random generator.

17. The method according to claim 10, wherein, during the reading out of a memory cell of a multilevel memory, a checking is carried out as to whether these represent, in accordance with the defined valid and invalid levels, a permissible or an impermissible data content, wherein in the case of a permissible data content said data content is made available for further processing, and in the case of an impermissible data content it is concluded that the memory cell was tampered with.

18. The method according to claim 10, wherein, when for a memory cell a time- or environmentally conditioned change was determined, in the case that an invalid level is given in this memory cell the subsequently higher permissible level is presumed to be actual level.