System and method for generating symmetric keys within a personal security device having minimal trust relationships

• US 20030086571A1
• Filed: 11/02/2001
• Published: 05/08/2003
• Est. Priority Date: 11/02/2001
• Status: Active Grant

• Current Assignee: Assa Abloy AB
• Original Assignee: ActivCard Co.
• Inventors: Le Saint, Eric F., Audebert, Yves Louis Gabriel
• Granted Patent: US 6,973,191 B2
• Time in Patent Office: Days
• US Class Current: 380/277
• CPC Class Codes: G06Q 20/02 involving a neutral party, e.g. certification authority, notary or trusted third party [TTP]
• CPC Class Codes: G06Q 20/341 Active cards, i.e. cards including their own processing means, e.g. including an IC or chip
• CPC Class Codes: G06Q 20/3829 involving key management
• CPC Class Codes: G06Q 20/40975 using encryption therefor
• CPC Class Codes: G07F 7/1008 Active credit-cards provided with means to personalise their use, e.g. with PIN-introduction/comparison system

Abstract

A data processing method and system for generating a unique symmetric key inside a PSD having limited trust relationships between PSD manufacture, PSD issuer, subsequent service providers and a trusted third party.

Claims

1. A data processing system for generating a unique symmetric cryptographic key using data stored inside a PSD from a plurality of separate sources, said system comprising:

a PSD including a non-mutable unique serial number, an operating system, data processing means, data storage means, communications means and cryptography means;

a PSD manufacturer including data processing means, communications means and cryptography means, wherein said PSD manufacturer operatively and securely installs a composite key generating algorithm and a first symmetric key inside said PSD, causing a first composite key to be generated and securely stored inside said PSD using said first symmetric key and said serial number as inputs into said composite key generating algorithm;

at least one secure transfer arrangement, wherein said PSD manufacturer sends said PSD and a copy of said first symmetric key and said PSD serial number to a PSD issuer and another copy of said first symmetric key and said serial number to a trusted third party;

said PSD issuer including data processing means, communications means and cryptography means, wherein said PSD issuer operatively and securely installs a second symmetric key inside said PSD using said first symmetric key to gain access to said PSD, causing a second composite key to be generated and securely stored inside said PSD using said first composite key and said second symmetric key as inputs into said composite key generating algorithm;

said at least one secure transfer arrangement, wherein said PSD issuer sends a copy of said second symmetric key and said serial number to said trusted third party;

said trusted third party in secure receipt of said first symmetric key and said serial number, wherein said trusted third party using an equivalent composite key generating algorithm to said PSD key generating algorithm generates said first duplicate composite key using said first symmetric key and said serial number as inputs into said equivalent composite key generating algorithm; and

said trusted third party in secure receipt of said second symmetric key and said serial number, wherein said trusted third party using said equivalent composite key generating algorithm generates said second duplicate composite key using said first duplicate composite key and said second symmetric key as inputs into said equivalent composite key generating algorithm.

2. The system according to claim 1, wherein said second symmetric key replaces said first symmetric key.

3. The system according to claim 1, wherein said second composite key replaces said first composite key.

4. The system according to claim 1, wherein said second duplicate composite key replaces said first duplicate composite key.

5. The system according to claim 1, wherein said secure transfer arrangement includes postal service, private courier and secure electronic transmission.

6. The system according to claim 1, wherein a third cryptographic key is securely installed inside said PSD causing a third composite key to be generated and securely stored inside said PSD using said second composite key and said third cryptographic key as inputs into said composite key generating algorithm.

7. The system according to claim 6, wherein said third cryptographic key is installed by said PSD issuer.

8. The system according to claim 6, wherein said third cryptographic key is installed by at least one service provider.

9. The system according to claim 7 or 8, wherein said third cryptographic key and said PSD serial number is sent using said at least one secure transfer arrangement to said trusted third party.

10. The system according to claim 9, wherein said trusted third party using said equivalent composite key generating algorithm generates said third duplicate composite key using said second duplicate composite key and said third cryptographic key as inputs into said equivalent composite key generating algorithm.

11. The system according to claim 10, wherein said third duplicate composite key replaces said second duplicate composite key.

12. The system according to claim 1 or 6, wherein a new cryptographic installed in said PSD causes a new composite key to be generated using a current composite key and said new cryptographic key as inputs into said composite key generating algorithm.

13. The system according to claim 12, wherein said new cryptographic key and said PSD serial number is sent using said at least one secure transfer arrangement to said trusted third party.

14. The system according to claim 13, wherein said trusted third party using said equivalent composite key generating algorithm generates a new duplicate composite key using a current duplicate composite key and said new cryptographic key as inputs into said equivalent composite key generating algorithm.

15. The system according to claim 12, wherein said new composite key replaces said current composite key.

16. The system according to claim 14, wherein said new duplicate composite key replaces said current duplicate composite key.

17. A method of generating a unique symmetric cryptographic key using data stored inside an operable PSD including a unique serial number, from a plurality of separate sources, said method comprising:

securely installing a composite key generating algorithm inside said PSD, wherein said composite key generating algorithm is known to a trusted third party,

securely installing a first symmetric key inside said PSD by a PSD manufacturer,

generating a first composite key by executing said composite key generating algorithm using said unique serial number and said first symmetric key as inputs into said composite key generating algorithm,

securely storing said first composite key inside said PSD,

sending a copy of said first symmetric key, said unique serial number and said PSD to a PSD issuer using at least one secure transfer arrangement,

sending a copy of said first symmetric key and said unique serial number to said trusted third party using said at least one secure transfer arrangement,

accessing said PSD using said first symmetric key by said PSD issuer,

securely installing a second symmetric key by said PSD issuer,

generating a second composite key by executing said composite key generating algorithm using said first composite key and said second symmetric key as inputs into said composite key generating algorithm,

securely storing said second composite key inside said PSD,

sending a copy of said second symmetric key and said unique serial number to said trusted third party using said at least one secure transfer arrangement,

securely receiving said first symmetric key and said unique serial number by said trusted third party,

generating a first duplicate composite key by said trusted third party using an equivalent composite key generating algorithm, said first symmetric key and said unique serial number as inputs into said equivalent composite key generating algorithm,

securely receiving said second symmetric key and said unique serial number by said trusted third party,

generating a second duplicate composite key by said trusted third party using said equivalent composite key generating algorithm and said second symmetric key as inputs into said equivalent composite key generating algorithm.

18. The method according to claim 17, further including replacing said second symmetric key with said first symmetric key.

19. The method according to claim 17, further including replacing said second composite key with said first composite key.

20. The method according to claim 17, further including replacing said second duplicate composite key with said first duplicate composite key.

21. The method according to claim 17, wherein said secure transfer arrangement includes postal service, private courier and secure electronic transmission.

22. The method according to claim 17 further including;

securely installing a third cryptographic key inside said PSD;

generating a third composite key using said second composite key and said third cryptographic key as inputs into said composite key generating algorithm;

securely storing said third composite key inside said PSD.

23. The method according to claim 22, wherein said third cryptographic key is installed by said PSD issuer.

24. The method according to claim 22, wherein said third cryptographic key is installed by at least one service provider.

25. The method according to claim 23 or 24, further including sending said third cryptographic key and said PSD serial number to said trusted third party using said at least one secure transfer arrangement.

26. The method according to claim 25 further including;

generating a third duplicate composite key by said trusted third party, using said second duplicate composite key and said third cryptographic key as inputs into said equivalent composite key generating algorithm.

27. The method according to claim 26 further including, replacing said second duplicate composite key with said third duplicate composite key.

28. The method according to claim 17 or 22, wherein installing a new cryptographic key into said PSD causes a new composite key to be generated using a current composite key and said new cryptographic key as inputs into said composite key generating algorithm.

29. The method according to claim 28 further including, sending said new cryptographic key and said PSD serial number to said trusted third party using said at least one secure transfer arrangement.

30. The method according to claim 29 further including, generating a new duplicate composite key by said trusted third party using a current duplicate composite key and said new cryptographic key as inputs into said equivalent composite key generating algorithm.

31. The method according to claim 28 further including, replacing said current composite key with said new composite key.

32. The method according to claim 30 further including, replacing said current duplicate composite key with said new duplicate composite key.