Common cryptokey generation system and communication system using common cryptokeys

• US 5,016,276 A
• Filed: 05/07/1990
• Issued: 05/14/1991
• Est. Priority Date: 07/31/1986
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Advance
• Original Assignee: Kabushiki Kaisha Advance
• Inventors: Matumoto, Tutomu, Imai, Hideki
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): SWANN, TOD R
• Application Number:
  US07/518,317
• Time in Patent Office: 372 Days
• Field of Search: 380/23-25, 380/28, 380/30, 380/21, 380/45, 380/47
• US Class Current: 380/45
• CPC Class Codes: H04L 9/083 involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP]
• CPC Class Codes: H04L 9/0847 involving identity based encryption [IBE] schemes

Abstract

A system for generating a cryptokey (k) to be shared among entities (A, B) engaged in communications, in particular one known as the key predistribution system. Indentifiers (y_A, y_S) for the entities engaging in communications under a center and a center algorithm (G) which only the center knows are generated, then secret algorithms (x_A, X_B) distinct to each entity are generated on added to IC cards or other cipher generation means (2, 3). A cipher generation means (2, 3) is provided for each entity. The identifiers (y_B, y_A) of the other entity are applied to compute a cryptokey, whereby a common cryptokey is generated.

Also disclosed is a system for communications using the above shared cryptokey.

Claims

1. A common cryptokey generation system for generating a common cryptokey to be used in securely communicating text from a first entity to a second entity, the first and second entities being remote from one another and having respective unique first and second entity indentifiers, the system comprising:

algorithm generation means for transforming the entity identifiers into a center algorithm, and for using the center algorithm to generate first and second algorithms uniquely corresponding to the respective first and second entities; and

first and second cryptokey generation means associated with the respective first and second entities and remote from each other for generating the common cryptokey, each of the first and second cryptokey generation means having storage means for storing the respective first and second algorithms and processing means operatively coupled to the storage means for processing the respective first and second algorithms in combination with the respective second and first entity identifiers to generate the common cryptokey.

2. A common cryptokey generation system according to claim 1, wherein at least one of the first and second cryptokey generation means includes a semiconductor integrated circuit apparatus.

3. A common cryptokey generation system according to claim 1, wherein the algorithm generation means include identifier transformation means for transforming each of the first and second entity identifiers to corresponding elements of a linear space.

4. A common cryptokey generation system for generating a common cryptokey to be used in securely communicating text from a transmitting entity to a plurality of receiving entities, each of the transmitting and receiving entities being remote from one another and each entity having a unique entity identifier, the system comprising:

algorithm generation means for transforming the entity identifiers into a center algorithm, and for using the center algorithm to generate a plurality of entity algorithms, each of the entity algorithms uniquely corresponding to one of the entities; and

a plurality of cryptokey generation means, each of the cryptokey generation means being uniquely associated with one of the transmitting and receiving entities and remote from others of the cryptokey generation means, for generating the common cryptokey, each of the cryptokey generation means having storage means for storing the corresponding entity algorithm and processing means operatively coupled to the storage means for processing the corresponding entity algorithm in combination with the entity identifiers of others of the entities to generate the common cryptokey.

5. A common cryptokey generation system according to claim 4, wherein the algorithm generation means include identifier transformation means for transforming each of the transmitting and receiving entity identifiers to corresponding elements of a linear space.

6. A common cryptokey generation system according to claim 4, wherein:

the storage means of each of the cryptokey generation means stores cipher text and a plurality of entity identifiers including its own entity identifier and the processing means of each of the cryptokey generation means uses the identifiers to confirm that the cipher text is addressed to that entity, extracts the transmitting entity identifier and applies the transmitting entity identifier to the cryptokey generation means of that entity to generate the common cryptokey.

7. A common cryptokey generation system according to claim 4, wherein the algorithm generation means include a plurality of algorithm generation apparatuses which operate mutually independently to respectively generate a plurality of independent first center algorithms and a combining apparatus operatively coupled to the algorithm generation apparatuses for combining the plurality of first center algorithms to generate the entity algorithms.

8. A common cryptokey generation system according to claim 7, wherein each of the first center algorithms corresponds to a vector linearly independent with respect to others of the vectors, and the algorithm generation means maintain the linear independence of the vectors.

9. A common cryptokey generation system according to claim 7, wherein the algorithm generation means generates the first center algorithms using an algorithm combination method.

10. A common cryptokey generation system according to claim 9, wherein each of the first center algorithms corresponds to a vector linearly independent with respect to others of the vectors, and the algorithm generation means maintain the linear independence of the vectors.

11. A common cryptokey generation system for generating a common cryptokey to be used in securely communicating text from a first entity to a second entity, the first and second entities being remote from one another and having respective unique first and second entity identifiers, the first entity having an enciphering device for enciphering the text according to the common cryptokey and transmitting a message including the enciphered text and the first and second entity identifiers, and the second entity having a deciphering device for receiving and deciphering the message according to the common cryptokey, the system comprising:

algorithm generation means for transforming the first and second entity identifiers into a center algorithm, and for using the center algorithm to generate first and second algorithms uniquely corresponding to the respective first and second entities;

first cryptokey generation means operatively coupled to the enciphering device for generating the common cryptokey in response to an externally-applied command, the first cryptokey generation means including first storage means for storing the first entity algorithm and first processing means operatively coupled to the first storage means and to the enciphering device for processing the first entity algorithm in combination with the second entity identifier to generate the common cryptokey and for communicating the common cryptokey to the enciphering device; and

second cryptokey generation means operatively coupled to the deciphering device and remote from the first cryptokey generation means for generating the common cryptokey, the second cryptokey generation means including second storage means for storing the second entity algorithm and second processing means operatively coupled to the second storage means and to the deciphering device for processing the second entity algorithm in combination with the first entity identifier to generate the common cryptokey and for communicating the common cryptokey to the deciphering device.

12. A common cryptokey generation system for generating a common cryptokey to be used in securely communicating text from a transmitting entity to a plurality of receiving entities, each of the transmitting and receiving entities being remote from one another and having a unique entity identifier, the transmitting entity having an enciphering device for enciphering the text according to the common cryptokey and transmitting a message including the enciphered text, the transmitting entity identifier, and the entity identifiers of the receiving entities, and each of the receiving entities having a deciphering device for receiving and deciphering the message according to the common cryptokey, the system comprising:

algorithm generation means for transforming the transmitting and receiving entity identifiers into a center algorithm, and for using the center algorithm to generate a first algorithm uniquely corresponding to the transmitting entity and a plurality of second algorithms uniquely corresponding to the respective receiving entities;

transmitting entity cryptokey generation means operatively coupled to the enciphering device for generating the common cryptokey in response to an externally-applied command, the transmitting entity cryptokey generation means including first storage means for storing the first algorithm and first processing means operatively coupled to the first storage means and to the enciphering device for processing the first algorithm in combination with the entity identifiers of the receiving entities to generate the common cryptokey and for communicating the common cryptokey to the enciphering device; and

a plurality of receiving entity cryptokey generation means, each of the receiving entity cryptokey generation means being associated with one of the receiving entities and being remote others of the transmitting and receiving entity cryptokey generation means, for generating the common cryptokey, each of the receiving entity cryptokey generation means having second storage means for storing one of the plurality of second algorithms uniquely corresponding to the respective receiving entity and second processing means operatively coupled to the second storage means and to the deciphering device for processing the one of the second algorithms in combination with the entity identifiers of the transmitting entity identifier and others of the receiving entities to generate the common cryptokey.

13. A method for generating a common cryptokey to be used in securely communicating text from a first entity to a second entity, the first and second entities being remote from one another and having respective unique first and second entity identifiers, the method comprising:

transforming the entity identifiers into a center algorithm, and using the center algorithm to generate first and second algorithms uniquely corresponding to the respective first and second entities;

prestoring the first and second algorithms at the respective first and second entities;

at the first entity, in response to an externally-applied command, processing the first algorithm in combination with the second entity identifier to generate the common cryptokey, enciphering the text using the common cryptokey, and transmitting a message including the enciphered text and the first and second entity identifiers to the second entity; and

at the second entity, processing the second algorithm in combination with the first entity identifier to generate the common cryptokey, and deciphering the enciphered text with the common cryptokey at the second entity.

14. A method according to claim 13, wherein the center algorithm includes a plurality of first center algorithms, each of the first center algorithms corresponding to a vector that is linearly independent of others of the vectors, and the entity algorithm generation step includes combing the plurality of first center algorithms to generate the entity algorithms.

15. A method for generating a common cryptokey to be used in securely communicating text from a transmitting entity to at least one of a plurality of receiving entities, each of the transmitting and receiving entities being remote from one another and having a unique entity identifier, the method comprising:

transforming the transmitting and receiving entity identifiers into a center algorithm, and using the center algorithm to generate a first algorithm uniquely corresponding to the transmitting entity and a plurality of second algorithms uniquely corresponding to the respective receiving entities;

prestoring the first algorithm at the transmitting entity and prestoring the second algorithms at the respective receiving entities;

at the transmitting entity, in response to an externally-applied command, processing the first algorithm in combination with the receiving entity identifiers of the at least one receiving entity to generate the common cryptokey, using the common cryptokey to encipher the text, and transmitting to the at least one receiving entity a message including the enciphered text and the entity identifiers of the transmitting entity and the at least one receiving entity; and

at each of the at least one receiving entities, processing the second algorithm corresponding to that receiving entity in combination with the transmitting entity identifier and the entity identifier for the at least one receiving entity to generate the common cryptokey.

16. A method according to claim 15, wherein the center algorithm includes a plurality of first center algorithms, each of the first center algorithms corresponding to a vector that is linearly independent of others of the vectors, and the entity algorithm generation step includes combining the plurality of first center algorithms to generate the entity algorithms.

17. A common cryptokey generation system comprising:

a secret algorithm generation apparatus for using a plurality of unique entity identifiers corresponding to a plurality of respective entities to generate a center algorithm, and for using the center algorithm to generate a plurality of secret algorithms each uniquely corresponding to one of the plurality of respective entities; and

a plurality of cryptokey generation means respectively associated with the entities for generating a common cryptokey, each of the cryptokey generation means storing an associated one of the secret algorithms, at least one of the cryptokey generation means generating the common cryptokey by applying to the associated secret algorithm at least one of the entity identifiers.

18. The common cryptokey generation system according to claim 17, wherein the cryptokey generation means include means for storing a corresponding one of the secret algorithms.

19. The common cryptokey generation system according to claim 17, wherein at least one of the cryptokey generation means comprises an integrated circuit card.

20. A common cryptokey generation system according to claim 17, wherein the algorithm generation means include identifier transformation means for transforming each of the entity identifiers to corresponding elements of a linear space.

21. A method for generating a common cryptokey, comprising:

using a plurality of unique entity identifiers corresponding to a plurality of respective entities to generate a center algorithm, and using the center algorithm to generate a plurality of secret algorithms each uniquely corresponding to one of the plurality of respective entities; and

at each of a portion of the entities, applying to the secret algorithm for that entity the identifier of at least one of the entities of the portion other than that entity to generate the common cryptokey.

22. The common cryptokey generation method according to claim 21, wherein the center algorithm is generated using a linear scheme.

23. The common cryptokey generation method according to claim 21, wherein generation of the center algorithm includes combining a plurality of first center algorithms, each of the first center algorithms corresponding to one of the entities.

24. A cryptographic communication system including a center and a group of entities which communicate with each other using a common cryptokey, each of the entities having a unique identifier, the system comprising:

algorithm generation means located at the center for transforming the entity identifiers into a center algorithm, and for using the center algorithm to generate a plurality of secret algorithms corresponding to respective ones of the entities by applying the respective identifiers to the center algorithm; and

a plurality of cryptokey generation means uniquely corresponding to and located at the respective ones of the entities for generating the common cryptokey, each of the cryptokey generation means applying to the corresponding secret algorithm the identifier of at least one of the other entities.

25. A common cryptokey generation system according to claim 24, wherein the algorithm generation means include identifier transformation means for transforming each of the entity identifiers to corresponding elements of a linear space.