Reliable storage medium access control method and device
OwnerJohan Paul Marie Gerard Linnartzinventor
Life of this patent
Estimating the term…
Abstract
A method of and device (110) for granting access to content on a storage medium (101), comprising obtaining cryptographic data (Y) from a property (102), such as a wobble, of the storage medium (101), reading helper data (W) from the storage medium (101), and granting the access based on an application of a delta-contracting function to the cryptographic data (Y) and the helper data (W). The delta-contracting function allows the choice of an appropriate value of the helper data (W), such that any value of the cryptographic data (Y) which sufficiently resembles said original primary input value leads to the same output value. Substantially different values of the cryptographic data (Y) lead to different values of the output.
Claims16
A method of granting access to content on a storage medium, said method comprising the steps of:
- configuring a processor to perform the steps of:
- obtaining cryptographic data from a property of the storage medium;
- reading helper data from the storage medium;
- and
- granting the access based on an application of a delta-contracting function to the cryptographic data and the helper data based on an output value, wherein the helper data defines ranges of values for the cryptographic data and the delta-contracting function defines a corresponding output value for each range of values for the cryptographic data so that the helper data can be made to adapt the cryptographic data for a particular storage medium carrier in tolerating small deviations in the obtained cryptographic data.
The method as claimed in claim wherein the access is granted if the output value of the delta-contracting function corresponds to a control value recorded on the storage medium.
A device arranged for granting access to content on a storage medium, said device comprising:
- first reading means for obtaining cryptographic data from a property of the storage medium;
- second reading means for reading helper data from the storage medium;
- and
- access control means for granting the access based on an application of a delta-contracting function to the cryptographic data and the helper data based on an output value, wherein the helper data defines ranges of values for the cryptographic data and the delta-contracting function defines a corresponding output value for each range of values for the cryptographic data so that the helper data can be made to adapt the cryptographic data for a particular storage medium carrier in tolerating small deviations in the obtained cryptographic data.
A playback and/or recording apparatus comprising:
- playback/recording means for playing back and/or recording data to a storage medium;
- and
- a device arranged for granting access to content on the storage medium, said device comprising:
- first reading means for obtaining cryptographic data from a property of the storage medium;
- second reading means for reading helper data from the storage medium;
- and
- access control means for granting access to the storage medium by the playback/recording means based on an application of a delta-contracting function to the cryptographic data and the helper data based on an output value, wherein the helper data defines ranges of values for the cryptographic data and the delta-contracting function defines a corresponding output value for each range of values for the cryptographic data so that the helper data can be made to adapt the cryptographic data for a particular storage medium carrier in tolerating small deviations in the obtained cryptographic data.
Dependencies are inferred from the claim text.