Method and apparatus for public key management

• US 6,370,249 B1
• Filed: 07/25/1997
• Issued: 04/09/2002
• Est. Priority Date: 07/25/1997
• Status: Expired due to Term

• Current Assignee: Entrust Incorporated (Entrust Corp.), Entrust Technologies Limited
• Original Assignee: Entrust Technologies Limited
• Inventors: Van Oorschot, Paul C.
• Primary Examiner(s): Decady, Albert
• Assistant Examiner(s): Callahan, Paul E.
• Application Number:
  US08/901,054
• Time in Patent Office: 1,719 Days
• Field of Search: 380/21, 380/23, 380/30, 380/277, 380/278, 380/259, 380/281, 380/282, 380/283, 380/284, 713/156, 713/157
• US Class Current: 380/277
• 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 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying
• CPC Class Codes: H04L 9/3265 using certificate chains, trees or paths; Hierarchical trust model

Abstract

A method and apparatus for public key management is accomplished when an associated authority provides, from time to time, a public key of at least one of a plurality of certificate authorities to a client. The associated authority provides the public key in a trustworthy manner over an on-line communication path and/or a store and forward communication path, which may be done using a self-signed signature public key certificate. Upon receiving the public key, the client maintains it in a storage medium associated with a client cryptographic engine. When a client application needs a security-related operation to be performed, it evokes the client cryptographic engine via an application program interface. Upon being evoked the client cryptographic engine determines whether a public key certificate associated with the security-related operation is verified as authentic based on the public key of at least one of the plurality of certification authorities. This is done by verifying the signature of the certification authority that signed the public key certificate associated with the security related operation. Once the signature is verified, the contents of the public key certificate can be authenticated. When the public key certificate is authenticated, the client cryptographic engine performs the security-related operation using a subject public key of the public key certificate associated with the security-related operation. Having done so, the client cryptographic engine provides an indication to the client application that it has successfully performed the security-related operation. If, however, the public key certificate was not authenticated, the client cryptographic engine provides the client application an indication that the security-related operation was not successfully performed.

Claims

1. A method for public key management, the method comprises the steps of:

a) from time to time, providing, in a trustworthy manner by an associated authority, a list of at least a plurality of trusted public keys of a plurality of different trusted certification authorities to at least one client, wherein at least one of the plurality of trusted certification authorities is not associated with a locale that the at least one client is associated with and wherein a certificate chain is not necessary to trust the plurality of trusted public keys on the list; and

providing trusted public keys via an on-line communication path or a stored and forward communication path;

b) by maintaining, by the at least one client, the trusted public keys of the trusted certification authorities in a storage medium associated with a client cryptographic engine;

c) evoking the client cryptographic engine by a client application to perform a security related operation;

d) determining, by the client cryptographic engine, whether a public key certificate associated with the security related operation is verified as authentic based on the trusted public keys of the trusted certification authorities;

e) when the public key certificate associated with the security related operation was verified as authentic, performing the security related operation using a subject public key of the public key certificate associated with the security related operation;

f) providing, by the client cryptographic engine to the client application, an indication that the security operation was performed successfully; and

g) when the public key certificate associated with the security related operation was not verified as authentic, providing, by the client cryptographic engine to the client application, an indication that the security operation was not performed successfully.

2. The method of claim 1 further comprises, within step (a), providing the trusted public keys of the trusted certification authorities to the at least one client at least one of:

initialization of the at least one client, public key set updating of the at least one of the plurality of certification authorities by the associated authority, and key recovery.

3. The method of claim 1 further comprises, within step (c), evoking the client cryptographic engine in response to receiving, by the at least one client, a message from another client, wherein the message is signed by the another client and the public key certificate of the another client is signed by a certification authority of the plurality of certification authorities, within step (d) indirectly verifying the public key certificate by authenticating a certification authority chain between the at least one of the plurality of certification authorities and the another one of the plurality of certification authorities.

4. The method of claim 1 further comprises, within step (a), providing a set of public keys of a set of the plurality of certification authorities to the client cryptographic engine.

5. A method for an associated authority to facilitate public key management, the method comprises the steps of:

a) obtaining a set of public keys of different trusted associated authorities for at least one client, wherein each public key of the set of public keys is based on a separate trusted path between the at least one client and one of the different trusted associated authorities, wherein at least one of the different trusted associated authorities is not associated with a locale that the at least one client is associated with and wherein a certificate chain is not necessary to trust the plurality of trusted public keys on the list;

b) providing the set of public keys to the at least one client in a trustworthy manner;

c) from time to time, updating the set of public keys to produce an updated set of public keys; and

d) providing the updated set of public keys to the at least one client.

6. The method of claim 5 further comprises providing the set of public keys to a group of clients.

7. The method of claim 6 further comprises providing a second set of public keys to a second group of clients.

8. The method of claim 5 further comprises obtaining the set of public keys from at least one of:

a system administrator, a policy authority, a designated certification authority, and local memory.

9. The method of claim 5 further comprises, within step (b), providing the set of public keys by way of a set of self signed certificates, wherein each of the self signed certificates include identity of the associated authority, the public key of the associated authority, and signature of the associated authority.

10. The method of claim 5 further comprises, within step (b), providing, as the associated authority, the set of public keys to the at least one client by at least one of:

a certification authority of the plurality of certification authorities that issued a public key certificate of the at least one client to the at least one client, a policy authority, and any one of the plurality of certification authorities.

11. An associated authority comprises:

a processing unit; and

memory that is operably coupled to the processing unit, wherein the memory stores programming instructions that, when read by the processing unit, causes the processing unit to (a) obtain a set of public keys of trusted associated authorities for at least one client, wherein each public key of the set of public keys is based on a separate trusted path between the at least one client and one of a set of different certification authorities;

wherein at least one of the different trusted associated authorities is not associated with a locale that the at least one client is associated with and wherein a certificate chain is not necessary to trust the plurality of trusted public keys on the list;

(b) provide the set of public keys to the at least one client in a trustworthy manner;

(c) from time to time, update the set of public keys to produce an updated set of public keys; and

(d) provide the updated set of public keys to the at least one client.

12. The associated authority of claim 11 further comprises, within the memory, programming instructions that, when read by the processing unit, causes the processing unit to update the set of public keys at least one of:

initialization of the at least one client, key recovery, and when the set of public keys is changed by a system administrator.

13. The associated authority of claim 11 further comprises, within the memory, programming instructions that, when read by the processing unit, causes the processing unit to provide, as the associated authority, the set of public keys to the at least one client by at least one of:

a certification authority of the plurality of certification authorities that issued a public key certificate of the at least one client to the at least one client, a policy authority, and any one of the plurality of certification authorities.

14. The associated authority of claim 11 further comprises, within the memory, programming instructions that, when read by the processing unit, causes the processing unit to provide the set of public keys by way of a set of self signed certificates, wherein each of the self signed certificates includes identity of the associated authority, the public key of the associated authority, and signature of the associated authority.

15. A digital storage medium that stores programming instructions that, when read by a processing unit, causes the processing unit to function as a client cryptographic engine, the digital storage medium comprises:

first means for storing programming instructions that, when read by the processing unit, causes the processing unit to obtain a set of public keys of trusted associated authorities for at least one client, wherein each public key of the set of public keys is based on a separate trusted path between the at least one client and one of a set of different certification authorities, wherein at least one of the different trusted associated authorities is not associated with a locale that the at least one client is associated with and wherein a certificate chain is not necessary to trust the plurality of trusted public keys on the list;

second means for storing programming instructions that, when read by the processing unit, causes the processing unit to provide the set of public keys to the at least one client in a trustworthy manner;

third means for storing programming instructions that, when read by the processing unit, causes the processing unit to, from time to time, update the set of public keys to produce an updated set of public keys; and

fourth means for storing programming instructions that, when read by the processing unit, causes the processing unit to provide the updated set of public keys to the at least one client.

16. The digital storage medium of claim 15 further comprises, within the fifth means, programming instructions that when read by the processing unit, causes the processing unit to update the set of public keys at least one of:

initialization of the at least one client, key recovery, and when the set of public keys is changed by a system administrator.

17. The digital storage medium of claim 15 further comprises, within the fifth means, programming instructions that when read by the processing unit, causes the processing unit to providing, as the associated authority, the set of public keys to the at least one client by at least one of:

a certification authority of the plurality of certification authorities that issued a public key certificate of the at least one client to the at least one client, a policy authority, and any one of the plurality of certification authority.

18. The digital storage medium of claim 15 further comprises, within the fifth means, programming instructions that when read by the processing unit, causes the processing unit to provide the set of public keys by way of a set of self signed certificates, wherein each of the self signed certificates includes identity of the associated authority, the public key of the associated authority, and signature of the associated authority.

19. A method for a client cryptographic engine to facilitate public keys management, the method comprises the steps of:

a) from time to time receiving, via a trustworthy manner, a list of trusted public keys of trusted certification authorities of a plurality of different certification authorities, wherein at least one of the different trusted certification authorities is not associated with a locale that the client cryptographic engine is associated with and wherein a certificate chain is not necessary to trust the plurality of trusted public keys on the list;

b) maintaining the trusted public keys of the trusted certification authorities in a local storage medium;

c) initiating execution of a security related operation when requested by a client application, wherein the client application interfaces with the client cryptographic engine via an application program interface;

d) as part of the initiating execution, determining whether a public key certificate associated with the security related operation is verified as authentic based on the trusted keys of the trusted certification authorities;

e) when the public key certificate associated with the security related operation was verified as authentic, performing the security related operation using a subject public key of the public key certificate associated with the security related operation;

f) providing an indication that the security operation was performed successfully to the client application; and

g) when the public key certificate associated with the security related operation was not verified as authentic, providing an indication that the security operation was not performed successfully to the client application.

20. The method of claim 19 further comprises, within step (f), providing, as the indication, the subject public key of the public key certificate.

21. The method of claim 19 further comprises, within step (d), determining that the public key indirectly verifies the public key certificate associated with the security operation, wherein the public key certificate includes a signature of another one of the plurality of certification authorities.

22. The method of claim 21 further comprises indirectly verifying the public key certificate by authenticating a certification authority chain between the at least one of the plurality of certification authorities and the another one of the plurality of certification authorities.

23. The method of claim 19 further comprises, within step (e), performing the security related operation to verify the signature of a received message directly when the certification authority is the at least one of the plurality of certification authorities, and verifying the signature of the received message indirectly via a certification authority chain when the certification authority is another one of the plurality of certification authorities.

24. The method of claim 19 further comprises, within step (e), performing the security related operation to encrypt an outgoing message.

25. The method of claim 24 further comprises, to encrypt the outgoing message, communicating, by the client cryptographic engine, with a directory to obtain a public key certificate of a recipient client of the outgoing message and authenticating a certification authority'"'"'s signature of the public key certificate of the recipient client.

26. The method of claim 24 further comprises, to encrypt the outgoing message, retrieving, by the client cryptographic engine from local memory, a public key certificate of a recipient client of the outgoing message and authenticating a certification authority'"'"'s signature of the public key certificate of the recipient client.

27. A client cryptographic engine comprising:

first memory means for storing programming instructions that, when read by a processor, causes the processor to interface with at least one application;

second memory means for storing trusted public keys of trusted certification authorities of a plurality of certification authorities, wherein the at least one public key of the trusted public keys is a signature verification public key of one of a plurality of different certification authorities, wherein at least one of the trusted certification authorities is not associated with a locale that the client cryptographic engine is associated with and wherein a certificate chain is not necessary to trust the plurality of trusted public keys on the list;

a processing unit; and

third memory means for storing programming instructions that, when read by the processing unit, causes the processing unit to (I) initiate execution of a security related operation when requested by the at least one application;

(ii) as part of the initiating execution, determine whether a public key certificate associated with the security related operation is verified as authentic based on the trusted public keys of the trusted certification authorities;

(iii) perform the security related operation when the public key certificate associated with the security related operation was verified as authentic;

(iv) provide, to the at least one application, an indication that the security related operation was performed successfully and (v) provide, to the at least one application, an indication that the security related operation was not performed successfully when the public key certificate associated with the security related operation was not verified as authentic.

28. The client cryptographic engine of claim 27 further comprises, within the first memory means, programming instructions that, when read by the processing unit, causes the processing unit to interface with a plurality of applications, wherein any of the plurality of applications can request of the security related operation.

29. The client cryptographic engine of claim 27 further comprises, within the third memory means, programming instructions that when read by the processing unit, causes the processing unit to update the trusted public keys of the trusted certification authorities, wherein updates are received from an associated authority.

30. The client cryptographic engine of claim 27 further comprises, within the third memory means, programming instructions that when read by the processing unit, causes the processing unit to determine that at least one of the trusted public keys indirectly verifies the public key certificate associated with the security related operation, wherein the public key certificate includes a signature of another certification authority.

31. The client cryptographic engine of claim 27 further comprises, within the third memory means, programming instructions that when read by the processing unit, causes the processing unit to perform the security related operation as at least one of:

verifying signature of the certification authority on the public-key certificate directly when the certification authority is the at least one of the plurality of certification authorities, and verifying the signature of the certification authority on the public-key certificate indirectly via a certification authority chain when the certification authority is another one of the plurality of certification authorities.

32. The client cryptographic engine of claim 27 further comprises, within the third memory means, programming instructions that when read by the processing unit, causes the processing unit to perform the security related operation to encrypt an outgoing message.

33. A digital storage medium that stores programming instructions that, when read by a processing unit, causes the processing unit to function as a client cryptographic engine, the digital storage medium comprises:

first means for storing programming instructions that, when read by the processing unit, causes the processing unit to, from time to time, receive, via a trustworthy manner, a list of trusted public keys of trusted certification authorities of a plurality of different certification authorities, wherein at least one of the different trusted certification authorities is not associated with a locale that the at least one client is associated with and wherein a certificate chain is not necessary to trust the plurality of trusted public keys on the list;

second means for storing programming instructions that, when read by the processing unit, causes the processing unit to maintain the trusted public keys in a local storage medium;

third means for storing programming instructions that, when read by the processing unit, causes the processing unit to initiate execution of a security related operation when requested by a client application, wherein the client application includes an application program interface to the client cryptographic engine;

fourth means for storing programming instructions that, when read by the processing unit, causes the processing unit to, as part of the initiating execution, determine whether a public key certificate associated with the security related operation is verified as authentic based on the trusted public keys;

fifth means for storing programming instructions that, when read by the processing unit, causes the processing unit to perform the security related operation using a subject public key of the public key certificate associated with the security related operation when the public key certificate associated with the security related operation was verified as authentic;

sixth means for storing programming instructions that, when read by the processing unit, causes the processing unit to provide an indication that the security operation was performed successfully to the client application; and

seventh means for storing programming instructions that, when read by the processing unit, causes the processing unit to provide an indication that the security operation was not performed successfully to the client application when the public key certificate associated with the security related operation was not verified as authentic.

34. The digital storage medium of claim 33 further comprises eighth means for storing programming instructions that when read by the processing unit, causes the processing unit to interface with a plurality of applications, wherein any of the plurality of applications can request of the security related operation.

35. The digital storage medium of claim 33 further comprises eighth means for storing programming instructions that when read by the processing unit, causes the processing unit to update the trusted public keys, wherein updates to the trusted public keys are received from an associated authority.

36. The digital storage medium of claim 33 further comprises, within the fifth means, programming instructions that when read by the processing unit, causes the processing unit to perform the security related operation as at least one of:

verifying signature of the certification authority on the public-key certificate directly when the certification authority is one of the trusted certification authorities, and verifying the signature of the certification authority on the public-key certificate indirectly via a certification authority chain when the certification authority is another one of the plurality of certification authorities.

37. The digital storage medium of claim 33 further comprises, within the fifth means, programming instructions that when read by the processing unit, causes the processing unit to perform the security related operation to encrypt an outgoing message.