Cryptography – Communication system using cryptography – Time segment interchange
Reexamination Certificate
1997-08-08
2001-06-19
Swann, Tod (Department: 2132)
Cryptography
Communication system using cryptography
Time segment interchange
C380S031000, C380S036000, C713S160000
Reexamination Certificate
active
06249583
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed in general to a system for processing analog signals, and more particularly to a system which employs sequential digital profiles to detect analog signals (or fragments of analog signals) satisfying requirements represented by said sequential digital profiles.
2. Description of the Background Art
Due to the real-time performance and storage requirement, recent demands for processing of on-line analog signal in such diversity of emerging applications as smart cards, signature identification, data security, speech recognition, medical diagnosis, and other transaction-oriented applications have required novel methods to be explored and introduced for the effective on-line computation of incoming analog signals. Namely for these new emerging transaction-oriented application the signal channels would typically remain silent until selective authorized users have made and initiated a particular request for the channel usage. The incoming signal sequence will then be comprised of selective user identification code, follow with a sequence of commands, and their relevant data. Due to their nature, such transactions can happen at any of the time instances, and occur in a totally random fashion. Therefore, it is really not possible to predict, anticipate and schedule these events employing traditional scheduling, optimization, and computation methods as described in the background arts.
As a result, although there are plenty of background arts for example, Oppenheim A. V. and chafer, R. W. “Digital Signal Processing”, Printice Hall, 1975, and Kung S., “VLSI Processor Array”, Prentice Hall 1987, which taught methods for the on-line processing of analog signal data, all of the methods would first require the traditional signal conversion from analog to digital domain, then store the entire command and data content at a local storage, and finally execute the commands when the user identifications are validated. These methods, though practical, require expensive high speed processing and memory circuits in order to reach the real time performance. Furthermore, these circuits must be constantly active in order to continuously monitor the signal channel for any incoming signal sequence. Finally, none of these methods have ever taught how to discriminate and eliminate the unauthorized or uninterested signals in the analog domain, namely prior to the analog to digital signal conversion, in order to avoid further storage and processing at the digital domain. It is conceived that these background arts will impose serious cost and power consumption disadvantage for their product implementation, and subsequently limit the market realization potential of these emerging technologies and applications.
In the relevant field of cryptography, similar situation remains. Although there are plenty of background arts which have taught how to apply highly sophisticated mathematical techniques and high speed scientific computer in order to generate the stored security key and to further encrypt the entire signal sequence. For example, Kahn B, Feiertag in “Private Communications in Mode Secure Systems” 1989, and Man Y. R. in “Cryptography and Secure Communications”, McGraw Hill, 1994. However, it is extremely difficult to accomplish real time on-line decryption without depending on vector or parallel computing. The situation becomes worse, particularly when use of multiple analog waveform representation for encryption further demands multiple algorithms and computation.
In light of these storage and performance problems, prior to their conversion from analog to digital domain, some form of novel front-end-computation method for the online analog signals is necessary. It would be also necessary to make such method programmable, whereby a single device can be programed in order to adapt to the various application environments. Finally, it is further necessary to make such computation method simple yet effective so that the product realization can become economical and affordable at the marketplace. To date, no single device possesses the necessary computation and storage power, yet would only require nominal cost for its implementation, in order to process the incoming analog bitstream at the necessary real time performance.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a system method for processing selective analog signals prior to their conversion from analog to digital domain, and more particularly a system method which employs sequential digital profiles to process incoming analog signals in order to detect signals (or fragments of signals) satisfying requirements represented by said sequential digital profiles.
It is still further an object of the present invention to apply said system method for the encryption and decryption of selective analog signals for privileged communications, wherein said decryption can be performed in real time prior to the signal conversion from analog to digital domain.
It is still further an object of the present invention to generalize said analog signals for including time-domain analog signals representing selective physical phenomena.
It is still further an object of the present invention to determine rules, conditions, and algorithms for the development of said sequential digital profiles.
It is still further an object of the present invention to perform on-line segmentation of said incoming analog signals according to selective properties of said sequential digital profiles.
It is still further an object of the present invention to represent results of said segmentation through on-line computation of a sequence of measurements in accordance with selective properties of said sequential digital profiles.
It is still further an object of the present invention to compare said results of segmentation with said sequential digital profiles in order to detect said incoming signals (or fragments of said incoming signals) satisfying requirements represented by said sequential digital profiles.
A preferred embodiment of the present invention is a system incorporating an input device, a memory device, a control unit, and a processing unit.
The input device acquires incoming analog signals. The memory device contains predefined sequential digital profiles. A single sequencial digital profile consists of the following components:
(i) a sequence of samples consisting of two values: a lower threshold value and a higher threshold value (the range of a sample);
(ii) a list of attributes divided into two subsets: in-segment attributes and off-segment attributes;
(iii) attribute values of said list of attributes for each sample of said sequence of samples.
The control unit supervises other components of the system according to a control algorithm, and interprets the results received from the processing unit. The general idea of the control algorithm performed by control unit is as follows:
(i) activate receiving an incoming analog signal by the input device;
(ii) activate a selected sequential digital profile;
(iii) send to the processing unit said list of attributes (both off-segment attributes and insegment attributes) of the active sequential digital profile;
(iv) select the first sample from said sequence of samples of the active sequential digital profile;
(v) send to the processing unit said range of the selected sample;
(vi) wait until attribute measurements are received from the processing unit;
(vii) if the received attribute measurements do not match said attribute values of the selected sample go to (iv);
(viii) if the selected sample is the last sample of said sequence of samples of the active sequential digital profile then either
assume that the incoming analog signal satisfies requirements represented by the active sequential digital profile and quit the algorithm
or
assume that the current fragment of the incoming analog signal satisfies requirements of the active sequential digital profile and go to (ii);
(ix) select the next sample of said sequence
Shaw Steven M.
Shaw Venson M.
Darrow Justin T.
Swann Tod
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