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Method for assigning encryption keys
| Details |
Inventors: Fagin, Ronald; Lotspiech, Jeffrey Bruce; Megiddo, Nimrod; Naor, Dalit; Naor, Simeon;
Assignee: International Business Machines Corporation (Armonk, NY)
Primary Examiner: Caldwell; Andrew
Assistant Examiner: Davis; Zachary A.
Attorney, Agent or Firm: Rogitz; John L.
An encryption key matrix has rows grouped into segments, with a set of one segment per column establishing a slot. Slots are assigned to device manufacturers, with the keys of the slots then being assigned to decryption devices made by the respective manufacturer. In generating the slots, the number "q" of segments in a column is first defined such that a predetermined maximum number of devices can be revoked devices (in that all the keys held by the device are revoked) while ensuring that a good device remains a functional device with a probability of at least (1-Q), wherein Q is a predefined device confidence. Once the number "q" of segments has been defined, the slots themselves are defined in a provably non-discriminatory fashion using an error-correcting code such as a Reed-Solomon code. With this invention, overlap between slots can be minimized to minimize the possibility that the key set of an innocent device might be inadvertently revoked when the keys in the slots of a "bad" manufacturer are revoked. |
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DETAILED DESCRIPTION The invention includes a computer system for undertaking the inventive logic set forth herein.
The invention can also be embodied in a computer program product that stores the present logic and that can be accessed by a processor to execute the logic.
Also, the invention is a computer-implemented method that follows the logic disclosed below.
A method is disclosed for assigning encryption keys from a key matrix in an encryption system to plural encryption device manufacturers.
The method includes determining a number "q" of row segments.
Each row segment includes a number of rows in the matrix.
The method also includes generating plural slots.
A slot is defined to be an assignment of row segments, one row segment for each column.
Device keys are assigned to manufacturers by periodically assigning a respective slot to a respective manufacturer.
In a preferred embodiment, slots are assigned to manufacturers on an as-needed basis.
Preferably, the number "q" is determined such that a survivability of the system is maximized.
In one manifestation, the number "q" is determined such that a predetermined maximum number of devices can have all their keys revoked while ensuring that a good device remains a functional device (i.
e.
, has at least one non-revoked key) with a probability of at least (1-Q), wherein Q is a predefined device confidence.
One type of revoked device can be a device made by a manufacturer which has had all its keys revoked, whereas another type of revoked device can simply be an example of a sporadically revoked device.
Once the number "q" is determined, the method includes receiving at least one parameter representing a characteristic of the key matrix, and then using the parameter and an error-correcting code to define the slots.
The error-correcting code can be a linear code such as a Reed-Solomon code.
In a particularly preferred embodiment, an error-correcting code is used that has a Hamming distance "d" that minimizes overlap between slots using a total number of slots derived from a predefined number "M" of manufacturers
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Audio Signal Processing 
