Certification process

• US 5,982,898 A
• Filed: 03/07/1997
• Issued: 11/09/1999
• Est. Priority Date: 03/07/1997
• Status: Expired due to Term

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Seymour, Stephen, Hsu, Yung-Kao
• Primary Examiner(s): Laufer, Pinchus M.
• Application Number:
  US08/812,640
• Time in Patent Office: 977 Days
• Field of Search: 380/25, 380/23, 380/49, 380/24
• US Class Current: 713/156
• CPC Class Codes: H04L 9/321 involving a third party or a trusted authority
• CPC Class Codes: H04L 9/3226 using a predetermined code, e.g. password, passphrase or PIN network architectures or network communication protocols for supporting authentication of entities using passwords in a packet data network H04L63/083
• CPC Class Codes: H04L 9/3263 involving certificates, e.g. public key certificate [PKC] or attribute certificate [AC]; Public key infrastructure [PKI] arrangements network architectures or network communication protocols for supporting authentication of entities using certificates in a packet data network H04L63/0823

Abstract

An improved secure communication arrangement separates the tasks of identity verification and certificate issuing, which allows a disassociating of the long-term binding between Alice and her public/private key pair. This is accomplished by a registration authority issuing a password to Alice once it is satisfied of Alice'"'"'s bona fide. Thereafter, whenever Alice wishes to communicate with Bob, she contacts a certification authority, identifies herself with the password and obtains a private key and a corresponding short-lived certificate. The certificate typically includes Alice'"'"'s name and a public key in plaintext, and a signature. The signature is derived by hashing the plaintext portion of the certificate to obtain a value, and encrypting the value with the CA'"'"'s private key. She then contacts Bob, submits her certificate, Bob performs the same hashing function to obtain a value, decrypts the signature with CA'"'"'s public key to obtain a decrypted value, and compares the value Bob created with the decrypted value. If the two match, Bob is assured that the person submitting the certificate may be communicated with by using the public key included in the certificate.

Claims

1. A method comprising the steps of:

a certification authority interacting with a user to receive a password from the user;

receiving a user password from said user;

receiving and storing a password from a third party to form a stored password;

determining whether said user password is valid by comparing said user password to said stored password;

when said user password is concluded to be valid by said step of determining, developing a certificate core that comprises information that results from encryption of first data with a private key of the certification authority (CA-PrKey), which first data comprises a public key of the user and a short-lived expiration time of the certificate, and

delivering the certificate core to the user to be used at least as part of the certificate.

2. The method of claim 1 where the expiration time is less than one month from the date the certificate is issued.

3. The method of claim 1 where the expiration time is the day after the day the certificate is issued.

4. The method of claim 1 where the expiration time explicitly includes the time of day.

5. The method of claim 1 further comprising the step of employing at least a part of the certificate core as a certificate or appending information to at least a part of the certificate core to form a certificate.

6. The method of claim 5 where a portion of the certificate core is not used as part of the certificate.

7. The method of claim 5 where the appending of information to form a certificate is carried out by the certification authority.

8. The method of claim 5 where the appending of information to form a certificate is carried out by the user.

9. The method of claim 1 where said first data also includes name of a user to whom the certificate is intended to be delivered.

10. The method of claim 1 where the first data also includes one or more from the set containing identity of the certification authority, name of a user to whom the certificate is intended to be delivered, other information about the user, a field that identifies the certificate to the certification authority, a service for which the certificate is valid, a purpose for which the certificate is valid, an authorization code, a server for which the certificate is intended, and a number of uses of the certificate in a server.

11. The method of claim 10 where a decision whether to include in said first data the identity of the certification authority is based on information provided by the user in the step of interacting.

12. The method of claim 1 where the first data further comprises information provided by the user, or information provided by the certification authority, or both.

13. The method of claim 1 where said encryption with CA-PrKey comprises encryption of a value which is derived from a hashing of the first data, and the certificate core further comprises second data which comprises the public key of the user and the short-lived expiration time of the certificate.

14. The method of claim 13 where the appending of information to form a certificate is carried out by the certification authority.

15. The method of claim 13 where the appending of information to form a certificate is carried out by the user.

16. The method of claim 13 where the second data further comprises one or more from a set comprising the name of the user, other information about the user, service for which the certificate is intended, service for which the certificate is valid, authorization code, expiration time of the certificate, or a number of uses of the certificate in a server.

17. The method of claim 16 where the information appended to the certificate core to form a certificate is included in the first data.

18. The method of claim 13 where the public key of the user is either provided by the user or by the certification authority.

19. The method of claim 13 where the second data further comprises information provided by the user, or information provided by the certification authority, or both.

20. The method of claim 13 where the information provided by the certification authority in the second data includes a public key that is associated with the private key of the user.

21. The method of claim 13 where the first data is identical to the second data.

22. The method of claim 1 further comprising the steps of:

said user providing specified information to a registration authority,

based on said specified information, said registration authority ascertaining whether said user deserves to possess said password, and

when said step of ascertaining concludes that said user deserves a password, said registration authority communicates said password to said certification authority.

23. The method of claim 22 where said registration authority creates said password.

24. The method of claim 22 where said password includes name of said user.

25. The method of claim 22 where in said step of said certification authority receiving said password from said user, said certification authority also receives name of said user, and where said registration authority communicates said user name to said certification authority when it communicates said password to said certification authority.

26. The method of claim 1 where said first data also includes name of a user to whom the certificate is intended to be delivered.

27. The method of claim 1 where said first data also includes a service for which the certificate is valid.

28. The method of claim 1 where said first data also includes a purpose for which the certificate is valid.

29. The method of claim 1 where said first data also includes a server for which the certificate is intended.

30. The method of claim 1 where said first data also includes a number of uses of the certificate in a server.

31. A method for responding to a connection request from a user comprising the steps of:

a certification authority receiving a password from a third party;

said user receiving a certificate from said certification authority in response to a user password presented to said certification authority by said user;

receiving said certificate, which contains information, including an expiration time;

determining the certificate'"'"'s bona fide;

refusing to continue the connection either when the certificate is not bona fide or when the expiration time has passed; and

carrying on the connection with aid from a public key contained in the certificate, without reference to information regarding revocation of certificates, when the expiration time of the certificate has not yet arrived.

32. The method of claim 31 where the step of determining the certificate'"'"'s bona fide comprises:

processing at least some plaintext information included in the certificate to obtain a value;

encrypting the value with a public key of a known certification authority to obtain a signature;

comparing the obtained signature with a signature contained in the certificate; and

accepting a first field of information contained in the certificate as a bona fide expiration time and a second field of information contained in the certificate as a bona fide user public key.

33. The method of claim 32 where the first field is either plaintext, encrypted with a private key of the certification authority that corresponds to the public key of the certification authority, or encrypted with a user private key that corresponds to the user public key.

34. The method of claim 32 where the second field is either plaintext or encrypted with a private key of the certification authority that corresponds to the public key of the certification authority.

35. The method of claim 31 where the step of determining the certificate'"'"'s bona fide comprises:

obtaining a public key of a certification authority;

decrypting the certificate; and

accepting a first field of information contained in the certificate as a bona fide expiration time and a second field of information contained in the certificate as a bona fide user public key.

36. The method of claim 31 further comprising, prior to the step of refusing the connection,

a step of determining from other information contained in the certificate, and without reference to information received by the processor with respect to the received certificate, whether the processor should respond to the connection request,

where the step of refusing to continue the connection is executed when the step of determining concludes that communication should be refused.

37. The method of claim 31 where the information contained in the certificate which is utilized in the step of determining is a purpose for which the certificate is to be employed, a service for which the certificate is employed, an application server identity, or number of uses.