Cryptographic communication terminal, cryptographic communication center apparatus, cryptographic communication system, and storage medium

• US 7,096,357 B1
• Filed: 03/03/2000
• Issued: 08/22/2006
• Est. Priority Date: 03/05/1999
• Status: Expired due to Fees

• Current Assignee: Oerlikon Contraves AG, Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Tochikubo, Kouya, Endoh, Naoki
• Primary Examiner(s): Louis-Jacques, Jacques H.
• Assistant Examiner(s): Brown, Christopher J.
• Application Number:
  US09/518,782
• Time in Patent Office: 2,363 Days
• Field of Search: 713/164, 713/189
• US Class Current: 713/164
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 63/06 for supporting key management in a packet data network cryptographic mechanisms or cryptographic arrangements for key management H04L9/08
• 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 9/0894 Escrow, recovery or storing of secret information, e.g. secret key escrow or cryptographic key storage
• CPC Class Codes: H04L 9/16 the keys or algorithms being changed during operation

Abstract

A cryptographic communication terminal serving as one of information transmitting and receiving terminals in cryptographic communication includes a cryptographic algorithm storage section for storing one or more types of cryptographic algorithm used for cryptographic communication, and outputting a designated cryptographic algorithm, a key information storage section for storing a key used for cryptographic communication corresponding to the cryptographic algorithm, and outputting a designated key, a control section for designating, with respect to the cryptographic algorithm storage section and the key information storage section, which cryptographic algorithm and key are to be used in the cryptographic communication, and an encryption/decryption section for decrypting received encryption information by using the cryptographic algorithm designated with respect to the cryptographic algorithm storage section and the key designated with respect to the key information storage section, and encrypting information to be transmitted.

Claims

1. A cryptographic communication terminal comprising:

a control section for designating an encrypted cryptographic algorithm and an encrypted encryption/decryption key to be used in cryptographic communication based on identification information;

a cryptographic algorithm storage section for storing not less than one type of cryptographic algorithm used for cryptographic communication in encrypted form, and outputting the encrypted cryptographic algorithm designated by the control section;

a key information storage section for storing and outputting the encrypted encryption/decryption key designated by the control section to be used for cryptographic communication and an encrypted key used for decrypting the encrypted cryptographic algorithm;

a key information decryption section for decrypting the encrypted encryption/decryption key used for cryptographic communication and the encrypted key used for decrypting the encrypted cryptographic algorithm to create an encryption/decryption key used for cryptographic communication and a decryption key used for decrypting the encrypted cryptographic algorithm;

a cryptographic algorithm decryption section for decrypting the encrypted cryptographic algorithm to generate a cryptographic algorithm by using the decryption key for decrypting the encrypted cryptographic algorithm; and

an encryption/decryption section for encrypting/decrypting communication messages by using the cryptographic algorithm and the encryption/decryption key.

2. The terminal according to claim 1, wherein the decryption key for the encrypted cryptographic algorithm is a key for secret key cryptography.

3. The terminal according to claim 1, wherein the decryption key for the encrypted cryptographic algorithm is a key for public key cryptography.

4. The terminal according to claim 1, wherein said control section instructs said cryptographic algorithm storage section to output a requested cryptographic algorithm upon receiving a transmission request for any one of the cryptographic algorithms stored in said cryptographic algorithm storage section, and

said encryption/decryption section encrypts the requested cryptographic algorithm as information to be transmitted.

5. The terminal according to claim 1, wherein when a partner with which said terminal communicates is an apparatus including said cryptographic communication terminal, said terminal:

requests the partner for a new cryptographic algorithm and/or a key for a corresponding encrypted algorithm;

decrypts a corresponding response by using said encryption/decryption section;

stores the requested cryptographic algorithm in said cryptographic algorithm storage section upon receiving the cryptographic algorithm; and

stores the requested key for the encrypt algorithm in said key information storage section upon receiving the key.

6. A cryptographic communication system comprising not less than two cryptographic communication terminals each defined in claim 1.

7. A cryptographic communication system comprising not less than two cryptographic communication terminals each defined in claim 1 and a cryptographic communication center apparatus communicating with a cryptographic communication terminal of the cryptographic communication system,

wherein when the algorithm decryption key is requested from a partner of the cryptographic communication center apparatus, said cryptographic communication center apparatus inputs the corresponding algorithm decryption key as the information to be transmitted to the partner to said encryption/decryption section;

and said cryptographic communication terminal acquires the cryptographic algorithm and a decryption key therefor from said cryptographic communication center apparatus.

8. The terminal according to claim 1, further comprising:

an ID storage section for storing the identification information.

9. A computer readable medium storing a program for implementing:

a control section for designating an encrypted cryptographic algorithm and an encrypted encryption/decryption key to be used in cryptographic communication based on identification information;

a cryptographic algorithm storage section for storing not less than one type of cryptographic algorithm used for cryptographic communication in encrypted form, and outputting the encrypted cryptographic algorithm designated by the control section;

a key information storage section for storing and outputting the encrypted encryption/decryption key designated by the control section to be used for cryptographic communication and an encrypted key used for decrypting the encrypted cryptographic algorithm;

a key information decryption section for decrypting the encrypted encryption/decryption key used for cryptographic communication and the encrypted key used for decrypting the encrypted cryptographic algorithm to create an encryption/decryption key used for cryptographic communication and an decryption key used for decrypting the encrypted cryptographic algorithm;

a cryptographic algorithm decryption section for decrypting the encrypted cryptographic algorithm to generate a cryptographic algorithm by using the decryption key for decrypting the encrypted cryptographic algorithm; and

an encryption/decryption section for encrypting/decrypting communication messages by using the cryptographic algorithm and the encryption/decryption key.

10. The computer readable medium according to claim 9, wherein:

said control section further comprises a program for, when a transmission request for any of the cryptographic algorithms stored in said cryptographic algorithm storage section is received, instructing said cryptographic algorithm storage section to output the requested cryptographic algorithm; and

said encryption/decryption section further comprises a program for encrypting the requested cryptographic algorithm as information to be transmitted.

11. The computer readable medium according to claim 9, further comprising a program for, when a key for the encrypted algorithm is requested from the partner, inputting the corresponding key for the encrypted algorithm, as the information to be transmitted to the partner, to said encryption/decryption section.

12. A cryptographic communication center apparatus, comprising:

at least one cryptographic communication terminal , the terminal including;

a control section for designating an encrypted cryptographic algorithm and an encrypted encryption/decryption key to be used in cryptographic communication based on identification information;

a cryptographic algorithm storage section for storing not less than one type of cryptographic algorithm used for cryptographic communication in encrypted form, and outputting the encrypted cryptographic algorithm designated by the control section;

a key information storage section for storing and outputting the encrypted encryption/decryption key designated by the control section to be used for cryptographic communication and an encrypted key used for decrypting the encrypted cryptographic algorithm;

a key information decryption section for decrypting the encrypted encryption/decryption key used for cryptographic communication and the encrypted key used for decrypting the encrypted cryptographic algorithm to create an encryption/decryption key used for cryptographic communication and a decryption key used for decrypting the encrypted cryptographic algorithm;

a cryptographic algorithm decryption section for decrypting the encrypted cryptographic algorithm to generate a cryptographic algorithm by using the decryption key for decrypting the encrypted cryptographic algorithm; and

an encryption/decryption section for encrypting/decrypting communication messages by using the cryptographic algorithm and the encryption/decryption key,

wherein when the algorithm decryption key is requested from a partner of the cryptographic communication center apparatus, said apparatus inputs the corresponding algorithm decryption key as information to be transmitted to the partner to said encryption/decryption section.

13. The apparatus according to claim 12, wherein:

said apparatus further comprises an update cryptographic algorithm storage section for storing a plurality of types of cryptographic algorithms decrypted by using a key for the encrypted algorithm; and

said control section, when a cryptographic algorithm is requested from said cryptographic communication terminal, instructs said update cryptographic algorithm storage section, in place of said cryptographic algorithm storage section, to output the requested cryptographic algorithm as information to be transmitted.

14. The apparatus according to claim 12, further comprising a key encryption section for, when the key for the encrypted algorithm is requested from said cryptographic communication terminal, encrypting the key for the encrypted algorithm to be transmitted, and inputting the encrypted key for the encrypted algorithm, as the information to be transmitted, to said encryption/decryption section.

15. The apparatus according to claim 14, wherein said key encryption section encrypts the key for the encrypted algorithm by using a key unique to a cryptographic communication terminal of the partner.

16. The system according to claim 14, wherein said cryptographic communication terminal acquires a cryptographic algorithm from another cryptographic communication terminal and acquires a corresponding decryption key from said cryptographic communication center apparatus.

17. The cryptographic communication center apparatus according to claim 12, further comprising:

an updated cryptographic algorithm storage section for storing a plurality of types of cryptographic algorithms encrypted by the key for the encrypted algorithm; and

means for, when the cryptographic algorithm decryption key is requested from the partner, inputting a corresponding key for the encrypted algorithm, as information to be transmitted to the partner, to said encryption/decryption section,

wherein said control section stores a program for, when a cryptographic algorithm is requested from said cryptographic communication terminal, instructing said update cryptographic algorithm storage means to output the requested cryptographic algorithm as information to be transmitted.