Authentication method for authenticating a first party to a second party

1. An authentication method for authenticating a first party to a second party, each party being one of a device and a software application, where an operation is performed on condition that the authentication succeeds, comprising the steps of:

providing at least one computer having a processor for performing the steps of:

verifying whether the first party is authenticated or not by determining whether a compliance certificate of the first party is out of date or not, based on a comparison measure of the second party, wherein the comparison measure comprises a range of allowed validity numbers, and wherein the comparison measure compares a date of issuance measure of the compliance certificate with the comparison measure of the second party, wherein said first party is authenticated only if it is determined by the comparison that the date of issuance measure is not out of date;

if the first party is determined to be not authenticated based on said verification, then conditionally qualifying the first party for a sub-authorization, dependent on a comparison of the date of issuance measure of the compliance certificate of the first party with the range of allowed validity numbers, wherein said conditional qualification of the first party for the sub-authorization is not allowed if it is determined that the date of issuance measure of the compliance certificate of the first party is lower than a minimum validity number of said range of allowed validity numbers indicating that the compliance certificate of the first party is revoked, and wherein said conditional qualification of the first party for the sub-authorization is allowed if it is determined that the date of issuance measure of the compliance certificate is higher than or equal to a maximum validity number of said range of allowed validity numbers;

if the compliance certificate of the first party is determined not to be revoked, a pre-set value of a grace-counter is used for controlling a number of times that the first party is being sub-authorized,

wherein, if the first party qualifies for the sub-authorization, the operation is still performed and the grace counter is decremented from an initialized predetermined number, and if the first party is authenticated, then setting the grace counter to the predetermined number.

2. The authentication method according to claim 1 , wherein said step of verifying comprises the step of: verifying if the first party is compliant according to a compliance certificate concerning the first party or not, wherein the first party is authenticated only if it is compliant.

3. The authentication method according to claim 2 , wherein said compliance certificate is a Groups Certificate.

4. The authentication method according to claim 2 wherein the second party holds a limited list of first parties, comprising the steps of: updating, at the second party, the comparison measure, and in conjunction with said updating, storing, at the second party, an updated set of compliance certificates containing compliance certificates concerning first parties on said list of first parties.

5. The authentication method according to claim 1 , wherein a maximum validity number of said range of allowed validity numbers is a current validity number stored at the second party.

6. The authentication method according to claim 1 , wherein a minimum validity number of said range of allowed validity numbers is a previous validity number stored at the second party.

7. The authentication method according to claim 1 , wherein the operation comprises accessing content.

8. The authentication method according to claim 7 , wherein said content is stored on an optical disc.

9. The authentication method according to claim 1 , wherein said first party is a software application and said second party is a device.