Abstract: A secure optical communication system and method are disclosed. Short optical pulses are first modulated with data, then dispersed in time so that they spread out over multiple bit periods, then the desired code is applied to the dispersed pulses. The encoding may include frequency shifts or phase shifts or other. The dispersed optical symbols overlap in time so an applied code chip thus acts on multiple symbols simultaneously. There are generally multiple code chips per dispersed symbol. The coding device does not need to be synchronized to the data rate. Multiple wavelength division multiplexed channels may be encoded simultaneously. The signal propagates to a decoder that is synchronized with encoder to apply a complementary code thereby canceling out the effect of the encoder. The encoder and decoder can be realized by varying the wavelength of an optical pump to a parametric amplifier, allowing for a wide-band frequency shift.

Abstract: Content filtering of data containers of multiple content types is performed using multiple filtering modules operating concurrently. An apparatus for content filtering has a set of content-specific filtering modules and a network interface for parsing a received data container into components and directing each component to a respective filtering module. A filtering module edits a component of a specific content type according to respective rules. A multiplexer combines edited components produced by the set of filtering modules to form an edited data container. A root module applies a set of basic rules to a data container and any attachments. In an alternative configuration, the apparatus employs multiple filtering modules each applying rules for all content types. Received data containers are distributed among the filtering modules and an output module arranges edited data containers of a data stream in proper sequential order.

Abstract: A method of providing secure communications over a network includes receiving, at a receiving computer, a public key of a sending computer, and a hash of a sending random number over a first communication channel, transmitting, from the receiving computer, a public key of the receiving computer and a receiving random number provided by the receiving computer over the first communication channel, and receiving, at the receiving computer, the sending random number provided by the sending computer over the first communication channel.

Abstract: Disclosed are embodiments of on-chip identification circuitry. In one embodiment, pairs of conductors (e.g., metal pads, vias, lines) are formed within one or more metallization layers. The distance between the conductors in each pair is predetermined so that, given known across chip line variations, there is a random chance (i.e., an approximately 50/50 chance) of a short. In another embodiment different masks form first conductors (e.g., metal lines separated by varying distances and having different widths) and second conductors (e.g., metal vias separated by varying distances and having equal widths). The first and second conductors alternate across the chip. Due to the different separation distances and widths of the first conductors, the different separation distances of the second conductors and, random mask alignment variations, each first conductor can short to up to two second conductors.

Abstract: Input signals are electronically watermarked using an uneven or non-uniform sampling rate. The uneven or non-uniform sampling may be pseudo-random. The uneven or non-uniform sampling meets the Nyquist criterion so that aliasing and loss of content are avoided. The resulting sampling pattern in the sampled data is detectable by a comparison with the original source data.

Abstract: A technique which implements a primitive for computing, e.g., a checksum. Specifically, this primitive replaces a mod(M) operation with a series of simple elementary register operations. These operations include mod 2n multiplications, order manipulations (e.g., byte or word swaps), and additions—all of which are extremely simple to implement and require very few processing cycles to execute. Hence, use of our inventive technique can significantly reduce the processing time to compute various cryptographic parameters, such as, e.g., a message authentication code (MAC), or to implement a stream cipher, over that conventionally required. This technique has both invertible and non-invertible variants.

Abstract: In a printing system, an information reception apparatus, such as a printer or the like, is allowed to more assuredly identify a specific user by using organism information of the user. Fingerprint readers read a fingerprint pattern of the user as image data. Pointing device including a keyboard, a mouse and the like is used when forming or editing print data. The print data and the fingerprint pattern subjected to encryption are transmitted from a computer to the printer via a data transmission channel. The fingerprint pattern transmitted from the computer is decoded. After authenticating the user by performing matching between the decoded fingerprint pattern and the fingerprint pattern read by the fingerprint reader, the print data is printed.

Abstract: A scrambling and a descrambling circuit for cordless telephone provides a higher security level than current phone scrambling circuitry. The higher security level is accomplished by separating an audio signal into low and high frequency bands. The frequency bands are selectively inverted or non-inverted during scrambling and descrambling according to common selection conditions. The processed signals are mixed into an overall mixed signal. The overall mixed signal is selectively inverted or non-inverted during scrambling and descrambling according to a common selection condition to increase the phone's transmission security level.

Abstract: An apparatus and method for creating voice privacy by performing frequency spectrum inversion in electronic voice transmission systems includes the steps of digitizing an analog signal and inverting the frequency spectrum of the digitized audio signal. From the inverted spectrum, a complex signal is created from which the real component is extracted to produce a real signal suitable for transmitting. The digital signal processing is performed entirely with software. The scrambling and descrambling processes are nearly identical, therefore, the same hardware and software may be used to scramble and descramble the signal. The apparatus may uses a "rolling code" to increase the effectiveness of the scrambling.

Abstract: Audio signals are descrambled by double sideband modulating the scrambled audio signal with a modulation carrier having a carrier frequency slightly above the highest audio signal present in the scrambled audio. This produces a double sideband signal that is passed through a low pass filter which in turn is modulated by a second carrier frequency lower than the first carrier signal by an amount equal to the offset spectrum of the original scrambled signal. The first low pass filter nulls out any residual carrier from the first modulator that results from the of intermodulation of the two modulation frequencies that would be audible at its descrambler output. The modulators used are low noise switch type modulators that improve the signal to noise ratio in the descrambled signal over the previously used linear modulators. The use of switch type modulators provides a lower cost device with improved performance.

Abstract: A universal decoder for scrambled television signals in which the signals are processed in a circuit by converting them to other frequencies and then removing the scrambling signal. One method uses one or more narrow filters at a fixed frequency with the television signal being heterodyned down to the frequency of the filters to place the scrambling signals in the rejection band of one of the filters. A second method eliminates scrambling signals by filters at video frequencies. In this method, the frequency in phase with the television signal carrier of a television channel is regenerated by filtering it with a narrow crystal filter and by means of an automatic phase comparison (APC) loop. The regenerated carrier is then used to synchronously demodulate the television signal. A third method for removing the scrambling signals is by use of one or more comb filters.

Abstract: A master decoder for scrambled television signals in which the signals are processed in a circuit by converting them to other frequencies and then removing the scrambling signal. One method uses one or more narrow filters at a fixed frequency with the television signal being heterodyned down to the frequency of the filters to place the scrambling signals in the rejection band of one of the filters. A second method eliminates scrambling signals by filters at video frequencies. In this method, the frequency in phase with the television signal carrier of a television channel is regenerated by filtering it with a narrow crystal filter and by means of an automatic phase comparison (APC) loop. The regenerated carrier is then used to synchronously demodulate the television signal. A third method for removing the scrambling signals is by use of one or more comb filters.

Abstract: A communication system for providing secured communication over a communication channel. The system includes a DES encryption device and a DES decryption device retrofittable into or within a conventional radio unit. The encryption device receives analog input at the transmitter end of the radio and converts the analog signal to digital signal, then encrypts this digital data, modulates the encrypted digital data using modified frequency modulation (MFM) which is then sent over the communication path. During decryption, the apparatus receives MFM data from the communication path, demodulates this digital data, decrypts the data and then outputs this decrypted digital data to the interface unit. The interface unit contains both a transmitter and a receiver which is capable of half duplex operation. The interface unit also contains a voice coder and a voice decoder which are of the sub-band type.

Abstract: Disclosed is a voice band splitting scrambler. To simplify the hardware thereof, the apparatus comprises a band splitting unit (11) for splitting an input voice signal into a plurality of band channels, and a scrambled voice signal generating unit (13) for carrying out spectrum-inverting and band-relocating operations on the respective channels to generate a scrambled voice signal. The scrambled voice signal generating unit (13) includes a modulating unit (15) for band-relocating the respective channels by noninverting carriers of inverting carriers set in different bands respectively; and an adding unit (17) for adding the signals of the noninverting channels and the signals of the inverted channels to each other.

Abstract: A speech privacy processing apparatus is disclosed including:a unit for obtaining the number of coefficients commonly included in a set of coefficients obtained by Fourier transformation and corresponding to high-frequency spectrum components of an input original speech signal and the set of coefficients corresponding to the high-frequency spectrum components after scrambling processing;scrambler for repetitively performing scrambling processing until the number of the common coefficients becomes smaller than a predetermined threshold value;a counter for counting the number of repetitions of the scrambling processing and transmitting the count to a receiver side;a unit for extracting a repetition count of scrambling processing from a reception signal;descrambler for performing descrambling processing in accordance with the extracted repetition count; anda unit for reproducing a speech signal.

Abstract: A method and apparatus for decoding of frequency inversion based scramblers is disclosed. A quadrature amplitude modulation detector determines the frequency of the tone used for inverting the scrambled signal by determining which of a plurality of quadrature detector pairs, each using a different conversion frequency, has the greatest magnitude difference between the quadraturely related signals. The frequency of the quadrature pair with the greatest difference is the frequency of the inverting tone during the inverting period of time. This frequency information is used to generate a reinversion tone to unscramble the scrambled signal.

Abstract: A toy helmet that permits the wearer to speak as to generate unintelligible noise so far as bystanders are concerned but which can be understood by another child wearing an identical helmet. Each helmet is equipped with internal and external microphones and an external speaker and internal earphones. Scrambler/descrambler circuitry is selectively connectable by means of a push-to-talk switch that delivers speech from the internal microphone to the external loudspeaker of the first helmet. The external microphone and the corresponding scambler/descrambler circuitry and push-to-talk switch of the second helmet delivers unscrambled speech to its internal earphone to permit the two helmet wearers to communicate intelligibly with one another. The scrambler/descrambler circuitry samples the low-pass filtered signals applied to its microphones at a sampling rate equal to the cut-off frequency of the low-pass filter.

Abstract: A method and apparatus for preventing recognition by a telephone system of a telephone dialing signal which inverts at least a portion of the telephone dialing signal in response to receiving the telephone dialing signal. Consequently, an inverted dialing signal is produced and is combined with the telephone dialing signal. Voice and data signals are unaffected. The telephone dialing signal is then connected to the telephone system and is unrecognizable as a valid number.

Abstract: The respective feature parameters extracted from a speech signal is converted into the corresponding line spectrum data in a first frequency band obtained by dividing the speech signal frequency band. Each of the line spectrum data is allocated previously to each one of the feature parameters. The extracted feature parameters are further converted into the corresponding line spectrum data in the other divided frequency bands other than the first frequency band. The converted line spectrum data are multiplexed for transmission. The corresponding line spectrum data in the divided frequency bands allocated to the same feature parameter are logically added to restore the feature parameters. Thus higher confidential communication is realized.

Abstract: Method of distorting a speech signal by rearranging and/or reversing frequency bands in this signal. The speech signal is divided into a plurality of sub-bands by filtering, and the sub-bands are individually sampled at a sampling frequencing which is at least double that of the sub-band bandwidth, for providing a plurality of first spectra each with periodic repetition of the respective sub-band. Alternating samples are polarity-reversed for providing a plurality of second spectra each with periodic repetition of the respective sub-band in reversed form. From one of these two types of spectrum a desired sub-band is then filtered out, and corresponds to the original sub-band, but is reversed and/or displaced in the frequency band as desired. All the obtained sub-bands are finally added to send the distorted signal.As an addition to the method of distorting, there is also proposed a method of recomposing the distorted speech signal.

Abstract: A wireless transmitter for PM (phase modulation) signal with a spectrum scrambler for relocation of input spectrum for privacy purposes is comprised of a differential circuit coupled with an input terminal, a spectrum scrambler coupled with output of said differential circuit, and FM (frequency modulation) modulator coupled with output of the spectrum scrambler. Due to the position of the differential circuit before the spectrum scrambler, modulation index of modulated PM signal and/or the frequency band of the modulated PM signal does not increase irrespective of spectrum scrambling.

Abstract: A scrambler system comprises in a transmitter part thereof as oscillator circuit for generating a local oscillation signal, a frequency dividing circuit for obtaining a frequency divided signal by frequency-dividing the local oscillation signal by 1/N, a triangular wave signal generating circuit for converting the frequency divided signal into a triangular wave signal and for controlling the oscillation frequency of the oscillator circuit by the triangular wave signal, a multiplying circuit for obtaining a frequency converted audio signal by multiplying the local oscillation signal with an input audio signal which is to be scrambled, a pilot signal generating circuit for generating from the frequency divided signal a pilot signal having a single frequency, and an adding circuit for obtaining a scrambled signal for transmission by adding the pilot signal and the frequency converted audio signal. A key is used for de-scrambling the scrambled signal in a receiver part of the scrambler system.

Abstract: A spectrum inversion type voice scrambler for secret speech communication comprises a first spectrum inversion section, a second inversion section and an adder for summing the outputs of the first and second inversion sections. A random signal generator produces two random signals for controlling, respectively, the spectrum inversion in the two inversion sections. The first inversion section is comprised of a modulator section composed of a variable frequency signal generator response to a random signal, a mixer receiving an input signal and the output of the variable frequency generator. The second inversion section includes three modulator sections the first and third of which are composed of a fixed frequency generator, a mixer and a low pass filter. The second modulator section is composed of a variable frequency generator responsive to the second random signal, a mixer and a low pass filter.