Methods and apparatus to issue digital certificates

1. An apparatus to issue a digital certificate, the apparatus comprising:

a certificate issuer to generate, at a first entity, a digital certificate to be signed and a first hash value of a first contribution value to be used in generating a certificate identifier for the digital certificate and to communicate to a plurality of entities including a second entity and a third entity, from the first entity, the digital certificate with a request for identifiers and the first hash value; and

a value receiver to receive, at the first entity, a second hash value uniquely identifying a second contribution value from a second entity, receive, at the first entity, a third hash value uniquely identifying a third contribution value from a third entity, and, after a period for accepting identifiers has ended, receiving, at the first entity, the second contribution value from the second entity and the third contribution value from the third entity;

the certificate issuer to combine, at the first entity, the first contribution value, the second contribution value and the third contribution value to generate the certificate identifier for the digital certificate and to issue the digital certificate with the certificate identifier.

2. An apparatus as defined in claim 1 , further including a value provider to generate the first contribution value using a random number generator.

3. An apparatus as defined in claim 1 , wherein the certificate issuer is to generate the certificate identifier based on an exclusive-or operation including the second contribution value and the third contribution value.

4. An apparatus as defined in claim 1 , wherein the certificate identifier is a certificate serial number.

5. An apparatus as defined in claim 1 , wherein the certificate issuer waits the period for accepting identifiers following communication of the digital certificate before communicating the first contribution value.

6. An apparatus as defined in claim 5 , wherein the certificate issuer is to publish the first hash value of the first contribution value prior to the end of the period for accepting identifiers.

7. An apparatus as defined in claim 1 , wherein the value receiver is to confirm that the second hash value corresponds to the second contribution value.

8. A method to issue a digital certificate, the method comprising:

generating, at a first entity, a digital certificate to be signed and a first hash value of a first contribution value to be used in generating a certificate identifier for the digital certificate;

communicating to a plurality of entities including a second entity and a third entity, from a first entity, the digital certificate with a request for identifiers and the first hash value;

receiving, at the first entity, a second hash value uniquely identifying a second contribution value from a second entity;

receiving, at the first entity, a third hash value uniquely identifying a third contribution value from a third entity;

after a period for accepting identifiers has ended, receiving, at the first entity, the second contribution value from the second entity and the third contribution value from the third entity;

combining, at the first entity, the first contribution value, the second contribution value, and the third contribution value to generate the certificate identifier for the digital certificate; and

issuing the digital certificate with the certificate identifier.

9. A tangible computer readable storage medium comprising instructions that, when executed, cause a machine to at least:

generate, at a first entity, a digital certificate to be signed and a first hash value of a first contribution value to be used in generating a certificate identifier for the digital certificate;

communicate to a plurality of entities including a second entity and a third entity, from a first entity, the digital certificate with a request for identifiers and the first hash value;

receive, at the first entity, a second hash value uniquely identifying a second contribution value from a second entity;

receive, at the first entity, a third hash value uniquely identifying a third contribution value from a third entity;

after a period for accepting identifiers has ended, receive, at the first entity, the second contribution value from the second entity and the third contribution value from the third entity;

combine, at the first entity, the first contribution value, the second contribution value, and the third contribution value to generate the certificate identifier for the digital certificate; and

issue the digital certificate with the certificate identifier.

10. A tangible computer readable storage medium as defined in claim 9 , wherein the instructions, when executed, cause the machine to generate the first contribution value using a random number generator.

11. A tangible computer readable storage medium as defined in claim 9 , wherein the instructions, when executed, cause the machine to generate the certificate identifier based on an exclusive-or operation including the second contribution value and the third contribution value.

12. A tangible computer readable storage medium as defined in claim 9 , wherein the certificate identifier is a certificate serial number.

13. A tangible computer readable storage medium as defined in claim 9 , wherein the instructions, when executed, cause the machine to wait the period for accepting identifiers following communication of the digital certificate before communicating the first contribution value.

14. A tangible computer readable storage medium as defined in claim 13 , wherein the instructions, when executed, cause the machine to publish the first hash value of the first contribution value prior to the end of the period for accepting identifiers.

15. A tangible computer readable storage medium as defined in claim 9 , wherein the instructions, when executed, cause the machine to confirm that the second contribution value corresponds to the second hash value.