Method and system for controlling key for electronic signature

• US 6,377,692 B1
• Filed: 03/11/1999
• Issued: 04/23/2002
• Est. Priority Date: 01/17/1997
• Status: Expired due to Term

• Current Assignee: Nippon Telegraph and Telephone Corporation, NTT Data Corporation (Nippon Telegraph and Telephone Corporation)
• Original Assignee: Nippon Telegraph and Telephone Corporation, NTT Data Corporation (Nippon Telegraph and Telephone Corporation)
• Inventors: Takahashi, Yoshio, Moribatake, Hidemi
• Primary Examiner(s): Peeso, Thomas R.
• Application Number:
  US09/142,929
• Time in Patent Office: 1,139 Days
• Field of Search: 380/277, 380/279, 380/284, 380/44
• US Class Current: 380/277
• CPC Class Codes: H04L 9/16 the keys or algorithms being changed during operation
• CPC Class Codes: H04L 9/3247 involving digital signatures

Abstract

Two keys which are updated in the same updating cycle at different times are prepared as signature keys (main key and auxiliary key) for electronic signature, and the updating cycle of each key is divided into, for example, three periods. The first and last periods after the updating are used for the auxiliary key while the intermediate period is used for the main key, and an electronic signature is carried out with the main key. The electronic signature is confirmed with either of two confirmation keys which are updated synchronously with updating the two keys used as the signature keys. This eliminates the need of stopping issuance of the electronic signature or limiting a service offer upon updating the signature keys.

Claims

1. An electronic signature key control method comprising preparing a plurality of keys whose contents are updated periodically at mutually different times;

and alternately switching the plurality of keys per switching cycle shorter than an updating cycle of each key to use one of the keys switched as a signature key for electronic signature.

16. The key control method according to claim 1, further comprising said switching cycles are set to the same time length with respect to all the keys.

17. The key control method according to claim 1 or 2, further comprising despite said switching, each of said keys can be used as the signature key.

18. The key control method according to claim 1, 2 or 3, further comprising said updating cycle is set to no longer than a time period derived by subtracting an effective term of an electronic signature produced based on the corresponding key from an average time over which security of the corresponding key can be ensured.

2. A key control method comprising dividing an updating period of each of a plurality of keys, whose contents are updated periodically at mutually different times, into three periods;

setting first and third divided periods as preliminary periods and an intermediate divided period as a use period for using as a signature key for electronic signature; and

switching the use periods of the respective keys so as to continue in time with each other but not to overlap with each other.

19. The key control method according to claim 2, further comprising an effective term of an electronic signature based on said signature key is equal to or shorter than a period which is the shorter of the first divided period and the last divided period.

20. The key control method according to claim 2, further comprising the sum of the first and last divided periods is set equal in time length to said intermediate divided period with respect to each key.

21. The key control method according to claim 2, further comprising the first divided period and the last divided period are set equal in time length to each other with respect to each key.

22. The key control method according to claim 2, further comprising the last divided period of one of the keys and the first divided period of another key are set equal in time length to each other.

23. The key control method according to claim 2, further comprising in the use period of one of the keys, another key is updated, and the use period of said updated another key is started at a time point of the termination of the use period of said one of the keys.

45. The electronic signature authentication system according to claim 23, wherein said M signature keys and M confirmation keys are possessed by a given system which produces an electronic signature using one of said M signature keys, and said given system supplies said M confirmation keys to said signature receiving means.

3. An electronic signature key control method comprising preparing a first key updated periodically and a second key updated periodically at different times as compared with said first key;

using either of said first and second keys as a signature key for electronic signature by alternately switching them per switching cycle shorter than an updating cycle of each key;

making public in pair a third key which is updated synchronously with an updating time of said first key and becomes a confirmation key when said first key is the signature key, and a fourth key which is updated synchronously with an updating time of said second key and becomes a confirmation key when said second key is the signature key; and

offering said third and fourth keys for confirming the electronic signature.

24. The key control method according to claim 3, further comprising a use termination time is added to each of said third and fourth keys.

4. An electronic signature key control method comprising:

preparing M, wherein M represents a natural number greater than one, signature keys updated periodically at mutually different times, and making public corresponding M confirmation keys at the same time, said M confirmation keys updated synchronously with updating times of said signature keys, respectively;

executing an electronic signature with respect to given signature object data by switching said prepared M signature keys per cycle shorter than an updating cycle of the corresponding signature key in a given order; and

confirming said electronic signature using one of the M confirmation keys made public.

5. An electronic signature key control system comprising key holding means for holding a plurality of keys to be used as signature keys for electronic signature;

key updating means for cyclically updating the contents of said plurality of keys at mutually different times;

key switching means for alternately switching said plurality of keys per switching cycle shorter than an updating cycle of each key; and

signature means for reading out the key, switched by said key switching means, from said key holding means according to a given rule, and executing an electronic signature with respect to given signature object data using the read-out key as the signature key.

25. The key control system according to claim 5 or 6, further comprising said key updating means divides said updating cycle into three periods, and each key is switched per time period shorter than the updating cycle of the corresponding key.

26. The key control system according to claim 25, further comprising said key updating means comprises mode selecting means for selectively applying a first mode for transferring the key contents of one of the divided periods to a subsequent divided period and a second mode for exchanging the key contents mutually upon shifting from a prior divided period to a subsequent divided period, and updates, during applying said first mode to one of the keys, the key contents of another key.

27. The key control system according to claim 25, further comprising said signature means uses each of said keys as the signature key during a period from the termination of a first period, after updating, of said divided periods to the start of a last period of said divided periods.

28. The key control system according to claim 5 or 6, further comprising when said electronic signature is used for member authentication between members, said signature means includes, in said signature object data, an effective term of said electronic signature and personal information including a signature confirmation key of the corresponding member and executes said electronic signature.

29. The key control system according to claim 5 or 6, further comprising when said electronic signature is used for authenticating an electronic ticket usable between members, said signature means includes, in said signature object data, information for identifying a service corresponding to said electronic ticket and a signature confirmation key of the member and executes said electronic signature.

31. The key control system according to claim 29, further comprising consecutive number information managed by a subject offering service information based on said electronic ticket is further included in said signature object data.

6. An electronic signature key control system comprising key holding means for holding a first key and a second key which are used as signature keys for electronic signature;

key updating means for updating the contents of said first key and said second key in the same cycle at mutually different times;

key switching means for alternately switching said first key and said second key per switching cycle shorter than an updating cycle of each key; and

signature means for reading out the key, switched by said key switching means, from said key holding means according to a given rule, and executing an electronic signature with respect to given signature object data using the read-out first or second key as the signature key.

30. The key control system according to claim 6, further comprising key holding means for holding a third key which is updated synchronously with said first key and becomes a confirmation key when said first key is the signature key, and a fourth key which is updated synchronously with said second key and becomes a confirmation key when said second key is the signature key, wherein when the electronic signature is carried out using said first or second key, said third and fourth keys are made public at the same time.

7. An electronic signature authentication system comprising signature receiving means for receiving an electronic signature produced with one of M, wherein M represents a natural number greater than one, signature keys which are updated at mutually different times, and corresponding M confirmation keys which are updated synchronously with updating the M signature keys including the signature key used for said electronic signature;

and signature confirming means for confirming said received electronic signature with one of said M confirmation keys, wherein the electronic signature confirmed by said signature confirming means is judged to be legitimate.

8. An electronic signature authentication system comprising signature receiving means for receiving a plurality of electronic signatures produced with signature keys, updated at different times, of M, wherein M represents a natural number greater than one, signature keys, and M confirmation keys which are updated synchronously with updating the M signature keys including the signature keys used for said electronic signatures;

and signature confirming means for confirming said received electronic signatures with one of said M confirmation keys, wherein the electronic signature confirmed by said signature confirming means is judged to be legitimate.

9. An electronic signature key control system comprising key holding means for holding a first key and a second key which are used as signature keys for electronic signature;

key updating means for updating the contents of said first key and said second key in the same cycle at mutually different times;

signature means for reading out the key, whose contents were updated by said key updating means, from said key holding means according to a given rule, and executing an electronic signature with respect to given signature object data using the read-out first or second key as the signature key; and

key holding means for holding a third key which is updated synchronously with said first key and becomes a confirmation key when said first key is the signature key, and a fourth key which is updated synchronously with said second key and becomes a confirmation key when said second key is the signature key, wherein when the electronic signature is carried out using said first or second key, said third and fourth keys are made public at the same time.

46. The key control system according to claim 9, further comprising when said electronic signature is used for member authentication between members, said signature means includes, in said signature object data, an effective term of said electronic signature and personal information including a signature confirmation key of the corresponding member and executes said electronic signature.

47. The key control system according to claim 9, further comprising when said electronic signature is used for authenticating an electronic ticket usable between members, said signature means includes, in said signature object data, information for identifying a service corresponding to said electronic ticket and a signature confirmation key of the member and executes said electronic signature.

48. The key control system according to claim 47, further comprising consecutive number information managed by a subject offering service information based on said electronic ticket is further included in said signature object data.

10. An electronic signature key control system comprising key holding means for holding a first key and a second key which are used as signature keys for electronic signature;

key updating means for updating the contents of said first key and said second key in the same cycle at mutually different times; and

signature means for reading out the key, whose contents were updated by said key updating means, from said key holding means according to a given rule, and executing an electronic signature with respect to given signature object data using the read-out first or second key as the signature key, wherein said key updating means divides said updating cycle into three periods, and each key is switched per time period shorter than the updating cycle of the corresponding key.

32. The key control system according to claim 10, further comprising said key updating means comprises mode selecting means for selectively applying a first mode for transferring the key contents of one of the divided periods to a subsequent divided period and a second mode for exchanging the key contents mutually upon shifting from a prior divided period to a subsequent divided period, and updates, during applying said first mode to one of the keys, the key contents of another key.

33. The key control system according to claim 10, further comprising said signature means uses each of said keys as the signature key during a period from the termination of a first period, after updating, of said divided periods to start of a last period of said divided periods.

34. The key control system according to claim 10, further comprising when said electronic signature is used for member authentication between members, said signature means includes, in said signature object data, an effective term of said electronic signature and personal information including a signature confirmation key of the corresponding member and executes said electronic signature.

35. The key control system according to claim 10, further comprising when said electronic signature is used for authenticating an electronic ticket usable between members, said signature means includes, in said signature object data, information for identifying a service corresponding to said electronic ticket and a signature confirmation key of the member and executes said electronic signature.

36. The key control system according to claim 35, further comprising consecutive number information managed by a subject offering service information based on said electronic ticket is further included in said signature object data.

11. An electronic signature key control system comprising key holding means for holding a plurality of keys to be used as signature keys for electronic signature;

a key updating means for cyclically updating the contents of said plurality of keys at mutually different times; and

signature means for reading out the key, whose contents were updated by said key updating means, from said key holding means according to a given rule, and executing an electronic signature with respect to given signature object data using the read-out key as the signature key, wherein said key updating means divides said updating cycle into three periods, and each key is switched per time period shorter than the updating cycle of the corresponding key.

37. The key control system according to claim 11, further comprising said key updating means comprises mode selecting means for selectively applying a first mode for transferring the key contents of one of the divided periods to a subsequent divided period and a second mode for exchanging the key contents mutually upon shifting from a prior divided period to a subsequent divided period, and updates, during applying said first mode to one of the keys, the key contents of another key.

38. The key control system according to claim 11, further comprising said signature means uses each of said keys as the signature key during a period from the termination of a first period, after updating, of said divided periods to start of a last period of said divided periods.

39. The key control system according to claim 11, further comprising when said electronic signature is used for member authentication between members, said signature means includes, in said signature object data, an effective term of said electronic signature and personal information including a signature confirmation key of the corresponding member and executes said electronic signature.

40. The key control system according to claim 11, further comprising when said electronic signature is used for authenticating an electronic ticket usable between members, said signature means includes, in said signature object data, information for identifying a service corresponding to said electronic ticket and a signature confirmation key of the member and executes said electronic signature.

41. The key control system according to claim 40, further comprising consecutive number information managed by a subject offering service information based on said electronic ticket is further included in said signature object data.

12. An electronic signature key control system comprising key holding means for holding a plurality of keys to be used as signature keys for electronic signature;

key updating means for cyclically updating the contents of said plurality of keys at mutually different times, said key updating means dividing said updating cycle into three periods; and

signature means for reading out the key, whose contents were updated by said key updating means, from said key holding means according to a given rule, and executing an electronic signature with respect to given signature object data using the read-out key as the signature key;

wherein said key updating means comprises a mode selecting means for selectively applying a first mode for transferring the key contents of one of the divided periods to a subsequent divided period and a second mode for exchanging the key contents mutually upon shifting from a prior divided period to a subsequent divided period, and updates, during applying said first mode to one of the keys, the key contents of another key.

42. The key control system according to claim 12, 13, 14 or 15, further comprising when said electronic signature is used for member authentication between members, said signature means includes, in said signature object data, an effective term of said electronic signature and personal information including a signature confirmation key of the corresponding member and executes said electronic signature.

43. The key control system according to claim 12, 13, 14 or 15, further comprising when said electronic signature is used for authenticating an electronic ticket usable between members, said signature means includes, in said signature object data, information for identifying a service corresponding to said electronic ticket and a signature confirmation key of the member and executes said electronic signature.

44. The key control system according to claim 43, further comprising consecutive number information managed by a subject offering service information based on said electronic ticket is further included in said signature object data.

13. An electronic signature key control system comprising key holding means for holding a first key and a second key which are used as signature keys for electronic signature;

key updating means for updating the contents of said first key and said second key in the same cycle at mutually different times, said key updating means dividing said updating cycle into three periods; and

signature means for reading out the key, whose contents were updated by said key updating means, from said key holding means according to a given rule, and executing an electronic signature with respect to given signature object data using the read-out first or second key as the signature key;

wherein said key updating means comprises a mode selecting means for selectively applying a first mode for transferring the key contents of one of the divided periods to a subsequent divided period and a second mode for exchanging the key contents mutually upon shifting from a prior divided period to a subsequent divided period, and updates, during applying said first mode to one of the keys, the key contents of another key.

14. An electronic signature key control system comprising key holding means for holding a plurality of keys to be used as signature keys for electronic signature;

key updating means for cyclically updating the contents of said plurality of keys at mutually different times, said key updating means dividing said updating cycle into three periods; and

signature means for reading out the key, whose contents were updated by said key updating means, from said key holding means according to a given rule, and executing an electronic signature with respect to given signature object data using the read-out key as the signature key;

wherein said signature means uses each of said keys as the signature key during a period from the termination of a first period, after updating, of said divided periods to the start of a last period of said divided periods.

15. An electronic signature key control system comprising key holding means for holding a first key and a second key which are used as signature keys for electronic signature;

key updating means for updating the contents of said first key and said second key in the same cycle at mutually different times, said key updating means dividing said updating cycle into three periods; and

signature means for reading out the key, whose contents were updated by said key updating means, from said key holding means according to a given rule, and executing an electronic signature with respect to given signature object data using the read-out first or second key as the signature key;

wherein said signature means uses each of said keys as the signature key during a period from the termination of a first period, after updating, of said divided periods to the start of a last period of said divided periods.