Certification of multiple keys with new base and supplementary certificate types

• US 6,981,147 B1
• Filed: 01/14/2000
• Issued: 12/27/2005
• Est. Priority Date: 01/29/1999
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Hamann, Ernst-Michael, Kreyss, Jutta, Vasudevan, Narayanan
• Primary Examiner(s): Barron, Jr., Gilberto
• Assistant Examiner(s): KIM, JUNG W
• Application Number:
  US09/483,358
• Time in Patent Office: 2,174 Days
• Field of Search: 713/150, 713/156, 713/155, 713/157, 713/175, 713/173
• US Class Current: 713/175
• CPC Class Codes: G06F 21/33 using certificates
• CPC Class Codes: G06F 21/45 Structures or tools for the administration of authentication
• CPC Class Codes: G06F 2221/2143 Clearing memory, e.g. to prevent the data from being stolen
• CPC Class Codes: H04L 9/006 involving public key infrastructure [PKI] trust models network architecture or network communication protocol for supporting authentication of entities using certificates in a packet data network H04L63/0823
• CPC Class Codes: H04L 9/3268 using certificate validation, registration, distribution or revocation, e.g. certificate revocation list [CRL]

Abstract

A method for creating, storing and reading a new certificate type for certification of keys is provided. In the new certificate type, several certificates, containing a minimum quantity of redundant data fields, are collated to form one certificate and all redundant information on the certificates is eliminated. An embodiment of the new certificate type is the group certificate. The group certificate is used where several keys are to be issued at the same time for the same user by the same certification instance. By means of the group certificate, all redundant data elements are eliminated and all data elements for a set of several keys subject to certification are grouped into one certificate. This substantially reduces the memory requirement, and handling of the certificates is simplified for the communication partners. A further embodiment of the new certificate type is the basic and supplementary certificate combination. This form of certification is used where certificates are issued at different times for the same user by the same certification body. The memory requirement is consequently somewhat more than for group certificates, but greater flexibility is gained in use of the keys.

Claims

1. A method of creating certificates with redundant information to certify keys of a user, wherein each of the certificates comprises a defined number of data elements which at least contain information on a certification body or issuer of the certificate, a user of the certificate and a key certified by the certificate, comprising the following steps:

a) creation by the certification body of a basic certificate for use in connection with the several keys of the user, the basic certificate containing a single recitation of a defined number of data elements therein which elements are identical or redundant if repeated in separate certificates one for each of the several keys of the user in conjunction with the certification body;

b) addition of an identifying characteristic to the basic certificate;

c) generation of a digital signature for the basic certificate;

d) addition of the digital signature to the basic certificate;

e) generation of a key pair;

f) creation of a supplementary certificate for the basic certificate which does not recite the redundant data elements contained in the basic certificate but does contain a key as set out in step e), the identifying characteristic as set out in step b) and additional data fields not registered by the basic certificate;

g) generation of a digital signature for the supplementary certificate;

h) addition of the digital signature to the supplementary certificate; and

i) use of the basic certificate created in step a) for other of the several keys in additional supplementary certificates that share with the supplementary certifactes of step f) the redundant information recited in the basic certificate but like the supplementary certificate of step f) do not recite the redundant data elements.

2. The method in accordance with claim 1, characterized in that the basic certificate does not contain any keys but comprises the following data elements:

name of the certification body,

user ID of the certification body,

name of the user,

user ID of the user, and

an identifying characteristic of the basic certificate.

3. The method in accordance with claim 2, characterized in that the supplementary certificates do not contain the redundant information recited in the basic certificate but comprise the following data elements:

a signature algorithm,

a key,

serial number of the key,

a validity period of the certificate,

extensions, and

the identifying characteristic of the basic certificate.

4. The method in accordance with claim 1 where one key is to be certified in step i) and the basic certificate of step a) already exists, including the following steps:

aa) definition of the basic certificate and reading of the identifying characteristics of the basic certificate;

bb) generation of a new key pair;

cc) creation of a supplementary certificate for the basic certificate with additional data fields not registered by the basic certificate, wherein one of the keys of step bb) is inserted into the supplementary certificate in;

dd) insertion of the identifying characteristics in accordance with step aa) into the supplementary certificate to locate the associated basic certificate;

ee) generation of a digital signature for the supplementary certificate; and

ff) addition of the digital signature to the supplementary certificate.

5. The method in accordance with claim 4, characterized in that any supplementary certificates each contain the following data elements:

a signature algorithm,

a key,

a serial number of the key,

validity period of the certificate,

extensions, and

the identifying characteristic of the basic certificate.

6. The method in accordance with claim 1, characterized in that the basic certificate and the supplementary certificates are stored in a non-volatile memory of a chipcard.

7. The method of claim 6 including the step of determining if the chipcard contians a relevant key to sign a message in the chip cards nonvolatile storage medium comprising:

a) check of the nonvolatile storage medium for presence of basic certificates;

b) if a basic certificate is present, identification of a supplementary certificate with a suitable signature key;

c) reading-in of the supplementary certificate into the chipcard RAM;

d) definition of the identification number of the basic certificate from the supplementary certificate; and

e) reading-in of the basic certificate into the RAM.

8. A computer program product on a computer usable hardware medium for creating certificates to certify several keys sharing redundant information, wherein a certificate comprises a defined number of data elements which at least contain information on a certification body or issuer to the certificate, a user of the certificate and a key certified by the certificate, said computer program product comprising:

a) software code for specification of a request for certification of one of the several keys by a certification body for a user;

b) software code for creation of a basic certificate that does not contain any key for the user but does contain a defined number of data elements which, in the certification process, are identical or redundant for the several keys of the user in conjunction with the respective certification body when initially not more than one of the several keys is to be certified with the basic certificate;

c) software code for the addition of an identifying characteristic to the basic certificate;

d) software code for the generation of a digital signature for the basic certificate;

e) software code for the addition of the digital signature to the basic certificate;

f) software code for generation of a key pair;

g) software code for creation of a supplementary certificate for the basic certificate with a key pair generated with the software as set out in f), the identifying characteristic as set out in c) and additional data elements not registered by the basic certificate of b);

h) software code for generation of a digital signature for the supplementary certificate;

i) software code for addition of the digital signature to the supplementary certificate; and

j) software code for use of the basic certificate created in step b) with a new key that shares the redundant data elements with the basic certificate by issuing an additional supplementary certificate with a new key pair generated with software as set forth in f), the identifying certificate as set forth in c) and additional data elements not registered by the basic certificate of b) or the supplementary certificate of g).

9. The computer program product in accordance with claim 8, characterized in that the basic certificate comprises the following data elements:

name of the certification body,

user ID of the certification body,

name of the user,

user ID of the user, and

identifying characteristic of the basic certificate.

10. The computer program product in accordance with claim 8, characterized in that the supplementary certificates comprise the following data elements:

a signature algorithm,

a public key from the key pair of f) or a public key from the new key pair of j),

a serial number of the key,

a validity period of the certificate,

extensions, and

identifying characteristic of the basic certificate.

11. The computer program product in accordance with claim 8, where more than one key with the same validity period is to be certified at one time, including the following software code:

aa) software code for generation of several key pairs;

bb) software code for generation of a single group certificate for the more than one key with all data elements necessary for the individual keys and keys generated in step aa), omitting the redundant data elements for the several keys by having only a single recitation of the redundent data elements in the group certificate;

cc) software code for generation of a digital signature for the group certificate; and

dd) software code for addition of the digital signature to the group certificate.

12. The computer program product software in accordance with claim 11, characterized in that the group certificate contains the following data elements:

name of the certification body,

user ID of the certification body,

name of the user,

user ID of the user,

type or version of the certificate,

number and types of keys,

a key,

a validity period of the certificate

serial Number, and

extensions.

13. The computer program product in accordance with claim 8, where a key is to be certified and the basic certificate already exists, including the following software code:

aa) software code definition of the basic certificate and reading of the identifying characteristics of the basic certificate;

bb) software code for generation of a key pair;

cc) software code for creation of a supplementary certificate for the basic certificate with additional data fields not registered by the basic certificate, wherein one of the keys is inserted into the supplementary certificate by step bb);

dd) software code for insertion of the identifying characteristics in accordance with step aa) into the supplementary certificate to locate the associated basic certificate;

ee) software code for generation of a digital signature for the supplementary certificate; and

ff) software code for addition of the digital signature to the supplementary certificate.

14. The computer program product in accordance with claim 13, characterized in that the supplementary certificate contains the following data elements:

a signature algorithm,

a key,

serial number of the key,

validity period of the supplementary certificate,

extensions, and

the identifying characteristic of the basic certificate.

15. A method of creating and using certificates to certify several keys for use in connection with a chipcard, wherein each of the certificates comprises a defined number of data elements which at least contain information on a certification body or issuer of the certificate, a user of the certificate and a key certified by the certificate, comprising the following steps:

a) creation by the certification body of a basic certificate that does not contain a key but is for use in connection with the several keys of the user, the basic certificate containing a single recitation of a defined number of data elements therein which elements would be identical or redundant if contained in separate certificates one for each of the several keys of the user in conjunction with the certification body;

b) addition of an identifying characteristic to the basic certificate;

c) generation of a digital signature for the basic certificate;

d) addition of the digital signature to the basic certificate;

e) generation of a key pair;

f) creation of a supplementary certificate for the basic certificate which does not recite the redundant data elements contained in the basic certificate but does contain a key as set out in step e), the identifying characteristic as set out in step b) and additional data fields not registered by the basic certificate;

g) generation of a digital signature for the supplementary certificate;

h) addition of the digital signature to the supplementary certificate;

i) use of the basic certificate created in step a) for other of the several keys in additional supplementary certificates that share with the supplementary certificate of step f) the redundant information recited the basic certificate but like the supplementary certificate of step f) do not recite the redundant data elements; and

j) storage of the basic and supplementary in a nonvolatile memory of the chipcard.

16. The method in accordance with claim 15, characterized in that the basic certificate comprises the following data elements:

name of the certification body,

user ID of the certification body,

name of the user,

user ID of the user, and

an identifying characteristic of the basic certificate.

17. The method in accordance with claim 15, characterized in that the supplementary certificates comprise the following data elements:

a signature algorithm,

a key,

serial number of the key,

a validity period of the certificate,

extensions, and

the identifying characteristic of the basic certificate.

18. The method in accordance with claim 15, where more than one key with the same validity period are to be certified at one time in step f), including the following steps:

aa) generation of several key pairs one for each of the keys;

bb) generation of a single certificate for all the several keys with all data elements necessary for the individual keys and keys generated in step aa), with only a single recitation of data elements redundant to all the several keys in the group certificate;

cc) generation of a digital signature for the group certificate;

dd) addition of the digital signature to the group certificate; and

ee) group certificate in the nonvolatile memory of the chipcard.

19. The method in accordance with claim 16, characterized in that the basic certificate contains the following data elements:

name of the certificate body,

user ID of the certification body,

name of the user,

user ID of the user,

type or version of the certificate,

number and types of keys,

a key,

a validity period of the certificate

serial number, and

extensions.

20. The method of claim 18 including the step of determining if the chipcard contains a relevant key in the chipcards nonvolatile storage medium to sign a message, comprising

a) check of the nonvolatile storage medium for presence of basic certificates;

b) if a basic certificate is present, identification of a supplementary certificate with a suitable signature key;

c) reading-in of the supplementary certificate into a RAM of the chipcard;

d) definition of the identification number of the basic certificate from the supplementary certificate;

e) reading-in of the basic certificate into the RAM;

f) when no basic certificate is identified checking of the storage medium for presence of group certificate; and

g) reading-in of a necessary group certificate into the RAM.