Cryptography – Key management – Having particular key generator
Reexamination Certificate
1998-01-20
2002-03-05
Hayes, Gail (Department: 2131)
Cryptography
Key management
Having particular key generator
Reexamination Certificate
active
06353669
ABSTRACT:
BACKGROUND
Encryption is well-known in the art. Where there is potential for a transmitted signal to be intercepted, encrypting (i.e., encoding) the signal before transmitting it reduces the chance that an interceptor can gain any useful information from the transmitted signal. For example, a user of the Internet may encrypt a signal that contains sensitive information, such as her credit card number, before transmitting the signal over the Internet.
In one prior art, an encryption “key” specifies exactly how the signal is encoded by a sender. The receiver of the signal requires the key in order to subsequently decode the signal. As long as the key remains unknown to potential interceptors, the security of the signal encoded in accordance with the key is virtually guaranteed.
Some encryption schemes utilize pre-defined keys. In order to keep the pre-defined keys unknown, they are exchanged between senders and receivers only through trusted intermediaries. Other encryption schemes utilize keys that are based on a random sequence of numbers generated by a random-number generator. The randomness of the key goes a long way towards ensuring that an interceptor cannot guess the key and use it, even if the interceptor manages to intercept the encoded signal itself.
Unfortunately, random number generators in practice consist of deterministic logic elements such as shift registers. Thus, the sequences of numbers generated by random number generators, while having good randomness properties, are in fact deterministic. That is, once the “seed” of the sequence is known, or if the seed is easily guessed, it is easy for an interceptor to predict the numbers of the random number sequence which follow. Conventionally, seeds have been computed based on information like a user's name, the time of invocation of the program, or other information that is reasonably easy for an interceptor to guess.
SUMMARY
An embodiment of the present invention is a method and apparatus that processes a video image signal to generate one or more random number generator seeds. Preferably, the video image signal represents a scene that is both unpredictable and “live”, or has changed). As a result, potential interceptors of signals encrypted with a random number sequence derived from the seed will find it difficult, if not impossible, to determine the random number sequence.
In accordance with an enhanced embodiment of the invention, a seed derived by processing a first video image signal is determined and is stored. Then, a second video image signal is received and a third video image signal is received. A difference is determined between the third video image signal and the second video image signal. If the difference exceeds a threshold (indicating that the scene represented by the video image signals is “live”), then the third video image signal is processed to generate a seed. Alternately, if the difference does not exceed the threshold, then the previously determined seed is provided as a determined seed.
REFERENCES:
patent: 4484027 (1984-11-01), Lee et al.
patent: 4833633 (1989-05-01), Morris
patent: 5561713 (1996-10-01), Suh
patent: 5732138 (1998-03-01), Noll et al.
patent: 5774549 (1998-06-01), Nielsen
Schneier, Bruce. Applied Cryptography. Second Edition. John Wiley and Sons. CIP 1995. pp 223-225.
Gunnison McKay & Hodgson, L.L.P.
Hayes Gail
Latham Bryan
Sun Microsystems Inc.
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