Abstract: An object of the present invention is to enable an authorized user to execute a quantum program, without letting the authorized user know the operation contents of the quantum program.

Abstract: A cryptographic system (CS) is provided. The CS (500) is comprised of a data stream receiving device (DSRD), a chaotic sequence generator (CSG) and an encryptor. The DSRD (602) is configured to receive an input data stream. The CSG (300) includes a computing means (3020, . . . , 302N?1) and a mapping means (304). The computing means is configured to use RNS arithmetic operations to respectively determine solutions for polynomial equations. The solutions are iteratively computed and expressed as RNS residue values. The mapping means is configured to determine a series of digits in the weighted number system based on the RNS residue values. The encryptor is coupled to the DSRD and CSG. The encryptor is configured to generate a modified data stream by incorporating or combining the series of digits with the input data stream.

Abstract: Alice generates a sequence of key bits forming an initial cryptographic key. Alice then uses the sequence of key bits and a sequence of cipher bits to control respective control parameters of a quantum encoding process applied to a sequence of quantum pulses, where the sequence of cipher bits used is known to Bob. Alice then releases the encoded pulses towards Bob over a quantum channel. Bob uses the previously agreed-upon sequence of cipher bits to control a control parameter, such as the quantum basis, of a quantum detection process applied to the pulses received from Alice, thus producing a detection outcome for each received pulse. Bob then derives a final cryptographic key from the detection outcomes. Because the cipher bits used to select the quantum bases used by both Alice and Bob are known by both parties, the method allows the final cryptographic key to be distributed with full basis alignment compared to 50% for BB84, thus allowing efficient quantum key distribution over multiple hops.

Abstract: A circuit for generating chaotic signals implemented using heterojunction bipolar transistors (HBTs) and utilized in low probability intercept communications. The HBT chaotic circuit generates truly random analog signals in the GHz range that are non-repeating and deterministic and may not be replicated by preloading a predetermined sequence. A fully differential autonomous chaotic circuit outputs two pairs of chaotic signals to be used in a communication system. As it is impossible to generate identical chaotic signals at the transmitter and receiver sites, the receiver itself sends the chaotic signal to be used for encoding to the transmitter. The receiver includes a chaotic signal generator and digitizes, upconverts, and transmits the generated chaotic signal to the transmitter. The transmitter uses the received chaotic signal to code data to be transmitted. The receiver decodes the transmitted data that is encoded by the chaotic signal to retrieve the transmitted data.

Abstract: An apparatus for measuring a range based on a chaotic ultra wideband (UWB) wireless communication technology is disclosed. The Apparatus includes a chaotic signal generating/modulating unit, a transceiving unit, a detecting unit, a transform unit, a comparison unit, and a range measurement unit. The transform unit converts the analog voltage signal from the detecting unit into digital signals based on a first sampling period. The comparison unit compares the analog voltage signal from the detecting unit with a predetermined threshold value and to output a comparison signal. The range measurement unit is configured to calculate a time point corresponding to a leading edge, which is a moment when initial data of a packet payload arrive, by using the digital signals based on the threshold value and by using the comparison signal, and to perform a range measurement calculation based on the time point corresponding to the leading edge.

Abstract: In quantum cryptography communication, a sequence of signals in the form of quantum states randomly selected from a plurality of quantum states each having a different phase modulation angle is transmitted from a data transmitting apparatus. In a data receiving apparatus, if the sequence of samples is received, a plurality of bases corresponding to a plurality of different phase modulation angles are randomly selected, and a homodyne detection process is performed using the selected bases. Information indicating the bases used in the homodyne detection process is sent to the transmitting apparatus. In the data transmitting apparatus, depending on the bases used in the receiving apparatus, bit values are assigned to the plurality of different quantum states selected by the transmitting apparatus, and information indicating the assigned bit values is sent to the data receiving apparatus.

Abstract: A system and method for generating analog-digital mixed chaotic signal and an encryption communication method thereof are provided. In the system and method, the complementarity between continuous chaotic systems (12, 22) and digital chaotic systems (11, 21) are reasonably utilized. In specific, the digital chaotic systems, which are separated from each other, control the local continuous chaotic systems respectively, so as to enable the continuous chaotic systems, which are also separated from each other, to stably and synchronously work for a long time. Thus, there is no need to transmit the synchronizing signal, and as a result the anti-attack capability is increased effectively. Further, the continuous chaotic systems disturb the local digital chaotic systems to prevent the digital chaotic systems from degradation. This compensates the drawbacks of digital chaotic systems.

Abstract: Methods and apparatuses for chaotic communication in a wireless personal area network, A chaotic information carrier is generated for a first predetermined frequency range using a ring-structure oscillator. The ring structure oscillator includes a non-linear element. Chaotic pulses are generated by modulating the chaotic information carrier for the first predetermined frequency range with a data signal. A shape of a spectral density envelope of the chaotic information carrier for the first predetermined frequency range is determined based on a set of parameters which include a first set of values.

Abstract: A PPB-CM communication system and method. The PPB-CM communication system includes a transmitter which splits a symbol period, which is a transmission unit of a communication signal, into at least a pair of parts, inserts a data signal into one of the parts, and transmits a communication signal having the data signal inserted; and a receiver which receives the communication signal from the transmitter and determines bit information of the symbol period according to which part of the symbol period has the data signal inserted, as determined by comparison of energy levels of the parts. Accordingly, a separate threshold is not required to determine the data bit of the symbol period. Thus, the communication signal can be accurately determined. Also, the communication system can be simply implemented without need of a delay line.

Abstract: A method of autocalibrating the timing of the laser in a quantum key distribution (QKD) system is disclosed. The laser generates photon signals in response to a laser gating signals from a controller. The method includes first performing a laser gate scan to establish the optimum laser gating signal arrival time corresponding to an optimum bit-error rate when exchanging photon signals between encoding stations of the QKD system. Once the optimum laser gating signal arrival time is determined, the laser gate scan is terminated and laser gate dithering is initiated. Laser gate dithering involves varying the arrival time of the laser gating signal around the optimum value of the arrival time. Laser gate dithering provides minor adjustments to the laser gating signal arrival time to ensure that the system operates at or near the optimum bit-error rate.

Abstract: A computer based method and apparatus to tie content protection information to recipient devices via a family of deterministic permutations of quadratic multivariate polynomial maps used for computing an HMAC (Hash Message Authentication Code) or a signed digest. This allows digital rights management (DRM) systems to customize the protection information (such as an HMAC or signed digest) for audio and video content, whereby such protection information for a piece of content differs for different recipient devices or for types of recipient devices.

Abstract: This invention relates to a method to protect an assembly implementing a cryptographic calculation process which uses a homographic function f of type: f(z)=(az+b)/(cz+d) when (cz+d) is not equal to 0 and f(?d/c)=a/c the function f operating on masked variables, wherein, for any k, if x is an input and y=f(x+k) is an output of the function f, to pass directly from a masked value x+m_i (additive masking of type XOR) to a masked value y+m_j, the method consists in comprises of performing this operation using a composition of several transformations operating on GF(2^k) with addition of the infinite, defined as (ax+b)/(cx+d), and of transformations which exchange two points.

Abstract: A method and system for providing communication over arbitrary distances with a desired probability of security is disclosed. In accordance with one embodiment of the invention shares of a random key are encoded, the random key for effecting communication of a message through a network employing a cryptographically strong forward security system having a limited effective communications distance. A distributed re-randomization of the encoded shares is then effected at a plurality of intermediate network nodes.

Abstract: A cryptographic method and systems using a keyed one-way function. A sending device uses the keyed one-way function to authenticate one or more receiving devices prerequisite to communication. A multidimensional hypercube is generated, from which is formed a multidimensional vector by randomly selecting one corner of the multidimensional hypercube. The keyed one-way function is computed using the multidimensional vector.

Abstract: Aspects of the invention provide a method and system for coding information in a communication channel. More particularly, aspects of the invention provide an method and system for synchronous running encryption and/or encoding and corresponding decryption and decoding in a communication channel or link. Aspects of the method may include encoding and/or encrypting a first data using a first or second encoding table and/or a first or second encryption table. The method may indicate which one of the first or second encoding tables or which one of the first or second encryption tables were utilized for encoding and/or encrypting the said first data. The encoded and/or encrypted first data may subsequently be transferred downstream and decoded by synchronous decoder/decryptor using a corresponding decoding and/or decryption table.

Abstract: According to one embodiment, a transmitter is configured to transmit content to a receiver. Available dubbing count is set in advance for the content such that the content can be dubbed a plurality of times. The transmitter includes a key exchanger, an encryption processor, and a dubbing management module. The key exchanger performs key exchange to share a common key with the receiver. The encryption processor encrypts, in response to a content request received from the receiver, the content with the common key to transmit the content to the receiver. The dubbing management module reduces, upon receipt of a right transfer request related to the use of the content from the receiver, the available dubbing count by dubbing count indicating the number of times of dubbing of the content. The dubbing count is contained in the right transfer request.

Abstract: A radio frequency (RF) communication system having a chaotic signal generator and a method of generating a chaotic signal. The RF communication system includes a chaotic signal generator which generates a chaotic signal having a plurality of frequency components at a predetermined frequency band, a modulator which generates a chaotic carrier by combining the chaotic signal with a data signal which indicates information, and a transmission circuit which includes an antenna to transmit the chaotic carrier made at the modulator. The frequency signal generator comprises an oscillator which converts a DC bias power into a high frequency power, and a resonating unit which generates a wideband signal having a plurality of frequency components by passing a predetermined frequency band of the high frequency power signal.

Abstract: A method is provided for coherently demodulating a chaotic sequence spread spectrum signal at a receiver (104). The method includes receiving a chaotic sequence spread spectrum signal including a plurality of information symbols. The method also includes generating a first string of discrete time chaotic samples. The first string of discrete time chaotic samples is identical to a second string of discrete time chaotic samples generated at a transmitter. The method further includes processing the chaotic sequence spread spectrum signal at the receiver to identify a time offset and a frequency offset relative to the first string of discrete time chaotic samples. Each of the discrete time chaotic samples of the first string of discrete time chaotic samples has a shorter sample time interval than the duration of the information symbols.

Abstract: A method is provided for generating a coherent chaotic sequence spread spectrum communications system. The method includes phase modulating a carrier with information symbols. The method also includes generating a string of discrete time chaotic samples. The method further includes modulating the carrier in a chaotic manner using the string of discrete time chaotic samples. Each of the discrete time chaotic samples has a shorter sample time interval than the duration of the information symbols. The generating step includes selecting a plurality of polynomial equations. The generating step also includes using residue number system (RNS) arithmetic operations to respectively determine solutions for the polynomial equations. The solutions are iteratively computed and expressed as RNS residue values. The generating step further includes determining a series of digits in the weighted number system based on the RNS residue values.

Abstract: A logic gate implements logical expressions. A least one logic gate input receives at least one input logic gate signal and at least one control signal. At least one output for produces a logic gate output signal. A nonlinear updater operates as a dynamically configurable element to produce a plurality of different logic gates as selected by the control signal. The nonlinear updater includes a nonlinear updater output. The nonlinear updater is configured to apply a nonlinear function to the input logic gate signal to produce the nonlinear updater output signal representing a logical expression being implemented by one of the plurality of different logic gates on the input logic gate signal. A comparator includes a comparator input that is adapted to receive a reference threshold value for producing the logical gate output signal based on a comparison of the nonlinear output signal to the reference threshold value.

Abstract: Systems and methods for obtaining information on a key in the BB84 (Bennett-Brassard 1984) protocol of quantum key distribution are provided. A representative system comprises a quantum cryptographic entangling probe, comprising a single-photon source configured to produce a probe photon, a polarization filter configured to determine an initial probe photon polarization state for a set error rate induced by the quantum cryptographic entangling probe, a quantum controlled-NOT (CNOT) gate configured to provide entanglement of a signal with the probe photon polarization state and produce a gated probe photon so as to obtain information on a key, a Wollaston prism configured to separate the gated probe photon with polarization correlated to a signal measured by a receiver, and two single-photon photodetectors configured to measure the polarization state of the gated probe photon.

Abstract: A method of authenticating data transmitted in a digital transmission system, in which the method comprises the steps, prior to transmission, of determining at least two encrypted values for at least some of the data, each encrypted value being determined using a key of a respective encryption algorithm, and outputting said at least two encrypted values with said data.

Abstract: A symmetric cryptosystem uses cascaded chaotic maps to encrypt plaintext and decrypt ciphertext. Received plaintext is encrypted using the cascaded chaotic maps to generate a ciphertext. The ciphertext can then be decrypted using the same cascaded chaotic maps in order to retrieve the plaintext.

Abstract: A sender's encrypted communication apparatus and a recipient's encrypted communication apparatus autonomously generate keys for encryption with respective key generators, store the generated encryption keys in respective encryption key memories, and store part of the generated encryption keys in respective authentication memories. The keys stored in the authentication memories are used for mutual authentication when the sender's encrypted communication apparatus and a recipient's encrypted communication apparatus are connected to each other.

Abstract: A process and system for generating a pseudo-random number is presented. Input data having entropy is gathered in an Entropy Pool and transformed once by a cryptographic hash function. The transformed data forms the internal state of the pseudo-random number generator. The generator forms the output by applying a second cryptographic hash function to this internal state. Finally, the generator updates the internal state by inputting the current internal state and data from the Entropy Pool into a third cryptographic hash function. The output of the third hash function forms the new internal state of the pseudo-random number generator.

Abstract: A method is provided for distributing quantum cryptographic keys. The method includes receiving a first quantum signal from an initial quantum key generating transmitter. Following correspondence with the initial quantum key generating transmitter, a first quantum key is generated. A second quantum signal is transmitted to a recipient quantum key generating transmitter. Following correspondence with the recipient quantum key generating receiver, a second quantum key is generated. The first quantum key is encoded using the second quantum key. The encoded first quantum key is transmitted to the recipient quantum key generating receiver using the second quantum key.

Abstract: Method and system for transmitting optical clock signals and quantum key signals on a single optical channel. A multi-photon optical clock signal is received at an electro-optic switch at a first clock rate. The electro-optic switch may be configured for an interval defined by a second clock rate for generating a single photon quantum key signal. The multi-photon optical clock signal and the single photon quantum key signal are combined such that the single optical channel transmits the single photon quantum key signal at a first interval and the multi-photon optical clock signal at a second interval. The quantum key signal is transmitted from a transmitter at a first timing, and detected by a detector at a receiver. An output signal of the detector is sampled at a second timing that is delayed relative to the first timing for reducing quantum bit error rate.

Abstract: An alternative design is given for an optimized quantum cryptographic entangling probe for attacking the BB84 protocol of quantum key distribution. The initial state of the probe has a simpler analytical dependence on the set error rate to be induced by the probe than in the earlier design. The new device yields maximum information to the probe for a full range of induced error rates. As in the earlier design, the probe contains a single CNOT gate which produces the optimum entanglement between the BB84 signal states and the correlated probe states.

Abstract: A quantum cryptography key distributing system includes an optical fiber; a transmission unit and a reception unit. The transmission unit is connected with the optical fiber, generates a transmission optical pulse signal from an optical pulse signal based on a first data in synchronism with an optical clock signal and transmits the transmission optical pulse signal to the reception unit via the optical fiber. Polarization of the transmission optical pulse signal is different from that of the optical pulse signal. The reception unit is connected with the optical fiber, transmits the optical pulse signal to the transmission unit via the optical fiber, phase-modulates a part of the transmission optical pulse signal based on a second data in synchronism with the optical clock signal, and detects a reception data corresponding to the first data based on the transmission optical pulse signal in synchronism with the optical clock signal.

Abstract: An authentication system and a method for signing data are disclosed. The system uses a hardware software partitioned approach. In its implementation the system of the invention compares favourably with performance and other parameters with a complete hardware or full software implementation. Particularly, advantageously there is a reduced gate count. Also as disclosed in the invention the system makes it difficult for hackers to attack the system using simple power analysis.

Abstract: A system for communicating a sequence of information symbols using a chaotic sequence spread spectrum signal. The system includes a transmitter (402) for transmitting a signal including the information symbols, the information symbols encoded into the signal using a first chaotic sequence of chips generated at the transmitter. The system also includes a receiver (404) configure to receive the signal and extract the information symbols from the signal, the information symbols extracted using a second chaotic sequence of chips generated at the receiver. In the system, the first and the second chaotic sequences are identical and synchronized in time and frequency, each of the sequence of symbols is associated with a randomly generated threshold symbol energy value, and the portion of chips in the first and the second chaotic sequences associated with each of the plurality of information symbols is selected based on the associated threshold symbol energy value.

Abstract: A system and method for exchanging a transformed message with enhanced privacy is presented. A set of input messages is defined. A set of output messages is defined. A message is selected from the input messages set. One or more words in the selected message are efficiently transformed directly into a transformed message different from the selected message, wherein the transformed message belongs to the set of output messages, at least one component of the selected message is recoverable from the transformed message, and the cost of determining whether the transformed message belongs to the input messages set or the output messages set exceeds a defined threshold.

Abstract: A communication system includes a transmitter having a signal generator for generating a signal for transmitting data, a transmission delay unit for repeatedly delaying the signal from the signal generator for a predetermined delay time within a symbol period and generating corresponding delayed signals, and a selector for selectively providing one of the delayed signals from the transmission delay unit to an antenna; and a receiver having a reception delay unit for receiving the signal from the transmitter and delaying the signal as long as the delay time of the transmission delay unit, and a data judgment block for discriminating data bits of the signal from the transmitter by comparing the signal from the transmitter with the delayed signal from the reception delay unit. According to the communication system, the delay time can be accurately adjusted even if the delay line is shortened, and the data bits of the communication signal can be accurately judged in the receiver side.

Abstract: A method of authenticating data transmitted in a digital transmission system, in which the method comprises the steps, prior to transmission, of determining at least two encrypted values for at least some of the data, each encrypted value being determined using a key of a respective encryption algorithm, and outputting said at least two encrypted values with said data.

Abstract: An encryption technique allowing use of classic Y-00 scheme performed using classic physical random numbers instead of quantum fluctuation in electrical communication and data storage in recording media, including a first modulation step for multilevel-modulating input data by associating with specific state pairs determined by physical random numbers, a second modulation step for outputting the output of the first step by irregularly associating with another signal by physical random numbers, and a channel coding step for channel-coding the output of the second step into desired codeword and outputting it as encrypted data, wherein the decoded signal obtained by channel-decoding the encrypted data can be discriminated which of specific state pairs the signal corresponds to and demodulated into the input data, and output by the first modulation by state pairs other than the specific state pairs and the second modulation by a physical random number different from the physical random number.

Abstract: A method of authenticating data transmitted in a digital transmission system, in which the method comprises the steps, prior to transmission, of determining at least two encrypted values for at least some of the data, each encrypted value being determined using a key of a respective encryption algorithm, and outputting said at least two encrypted values with said data.

Abstract: A method for re-encrypting encrypted data in a secure storage file system, including obtaining selected data to re-encrypt from the secure storage file system using a user data access record and the encrypted data, decrypting the selected data using a symmetric key, re-encrypting the selected data using a new symmetric key to obtain new encrypted data, encrypting the new symmetric key using a public key to obtain a new encrypted symmetric key, storing the new encrypted data and the new encrypted symmetric key if the public key is associated with a file system user having read permission, and storing an encrypted hash data if the file system user has write permission.

Abstract: A method of performing a cryptographic operation on a point in an elliptic curve cryptosystem using an elliptic curve. The method comprises the steps of obtaining information that uniquely identifies the elliptic curve and performing computations on the point to obtain the result of the cryptographic operation. The computations use the information. The computations produce an incorrect result if the point is not on the elliptic curve.

Abstract: Alice generates a sequence of key bits forming an initial cryptographic key. Alice then uses the sequence of key bits and a sequence of cipher bits to control respective control parameters of a quantum encoding process applied to a sequence of quantum pulses, where the sequence of cipher bits used is known to Bob. Alice then releases the encoded pulses towards Bob over a quantum channel. Bob uses the previously agreed-upon sequence of cipher bits to control a control parameter, such as the quantum basis, of a quantum detection process applied to the pulses received from Alice, thus producing a detection outcome for each received pulse. Bob then derives a final cryptographic key from the detection outcomes. Because the cipher bits used to select the quantum bases used by both Alice and Bob are known by both parties, the method allows the final cryptographic key to be distributed with full basis alignment compared to 50% for BB84, thus allowing efficient quantum key distribution over multiple hops.

Abstract: A communication system which transmits and receives a communication signal having an intra-guard-interval (IGI) inserted is provided. The communication system includes a signal generator which is configured to generate a signal to carry data; and a signal output part which is configured to split a symbol period, which is a transmission unit of the communication signal into a plurality of sections, and to selectively insert the signal which is generated into the plurality of sections, and to output the communication signal.

Abstract: A method is provided for encryption/decryption for secure the privacy of the information flow between two communicating nodes, and authentication to establish the identity of the communicating nodes in digital communications systems. A common secret or encryption key is generated at the two nodal ends of the communication link without prior dissemination. The authenticity of the communicating entities are maintained over time based on unique non-idealities of the communicating nodes in conjunction with the propagation characteristics of a link between them.

Abstract: The invention is a cryptographic system using chaotic dynamics. A chaotic system is used to generate a public key and an adjustable back door from a private key. The public key is distributed and can be used in a public key encryption system. The invention can also be used for authentication purposes. The adjustable back door of the invention can be used in conjunction with the public key to derive the private key. The degree of difficulty involved in deriving the private key is dependent on the adjustable back door. That is the value of the back door can be adjusted to vary the difficulty involved in deriving the private key.

Abstract: Aspects of the invention provide a method and system for coding information in a communication channel. More particularly, aspects of the invention provide an method and system for synchronous running encryption and/or encoding and corresponding decryption and decoding in a communication channel or link. Aspects of the method may include encoding and/or encrypting a first data using a first or second encoding table and/or a first or second encryption table. The method may indicate which one of the first or second encoding tables or which one of the first or second encryption tables were utilized for encoding and/or encrypting the said first data. The encoded and/or encrypted first data may subsequently be transferred downstream and decoded by synchronous decoder/decryptor using a corresponding decoding and/or decryption table. The corresponding decoding and/or decryption table may be determined based on the indicated first and/or second encoding and/or encrypting tables.

Abstract: A secure transaction method is provided for publicly-accessible transaction terminals. The method uses quantum key distribution (QKD) between a hand-portable QKD device and a complimentary QKD apparatus incorporated the transaction terminal. After the QKD device has been brought up to the transaction terminal, the QKD device and the complimentary QKD apparatus of the terminal are is used to provide the device and terminal with new secret shared random material. The new secret shared random material is then used to establish a secure classical communication channel between the device and transaction terminal for conducting a transaction. An ATM terminal and POS terminal that use quantum key distribution are also disclosed.

Abstract: For a defined cryptographic process including an original substitution table, split masked substitution tables are provided to resist cryptographic attacks. The split masked substitution tables are defined with reference to a set of random value data words and a mask value. An entry in the split masked substitution tables is defined by selecting bits from the corresponding entry in the original masked substitution table, as masked by the corresponding one of the set of random value data words and by selecting bits from the corresponding one of the set of random value data words as masked by the mask value. The split masked substitution tables are usable in a modified cryptographic process based on the defined cryptographic process to permit a masked output to be generated. The split masked substitution tables are refreshed by each entry in the tables being refreshed upon access during execution of the modified cryptographic process.

Abstract: Methods for calibrating the modulators in a QKD system (100) are disclosed. The methods include setting the voltage (VB) of Bob's modulator (MB) to a positive value and then adjusting the voltage (VA) of Alice's modulator (MA) in both the positive and negative direction to obtain overall relative phase modulations that result in maximum and minimum photon counts (N) in the two single-photon detectors (32a, 32b). Bob's modulator voltage is then set to a negative value and the process repeated. When the basis voltages (VB(1), VB(2), VA(1), VA(2), VA(3) and VA(4)) are established, the QKD system is operated with intentionally selected incorrect bases at Bob and Alice to assess orthogonality of the basis voltages by assessing whether or not the probability of photon detection at the detectors is 50:50. If not, the modulator voltages are adjusted to be orthogonal. This involves changing Bob's basis voltage (VB(1) and/or VB(2)) and repeating the process until a 50:50 detector count distribution is obtained.

Abstract: Digital communication schemes using chaotic signals as carriers can be broadly classified into two categories. In the first category, the chaotic signals carrying the information have to be synchronously regenerated at the receiver, which may be applicable to low noise environment. The second category requires no synchronous regeneration of the carrying chaotic signals in the receiver. An example of the second category utilizes a specific bit structure, which may not be able to resist unintended reception because the fabricated bit structure can be relatively easily detected. This invention involves systems and methods for transmitting digital messages modulated as chaotic signals, and the demodulation methods. One individual chaotic signal generator having a specific chaotic characteristic value is responsible for generating a chaotic signal for each possible value of the digital message according to a chaotic algorithm.

Abstract: A sender and a receiver includes first and second arrays of coupled oscillators, respectively, that are substantially identically constructed so as to exhibit substantially the same dynamical response to excitation. A chaotic waveform generated at the sender is transmitted to the receiver, which generates a second chaotic waveform, and compares the received waveform with the generated second waveform. If the first and second waveforms match the sender is an authorized sender. An integrated circuit includes an array of coupled oscillators that in combination generate a waveform in response to at least one excitation signal. The array of coupled oscillators represents, in response to application of the excitation signals, a multi-dimensional security key that is shared between the sender of the waveform and the receiver of the waveform.

Abstract: A communication system includes an encryptor and a decryptor. For improved encryption security, the encryptor includes a multitap delay line to produce mutually delayed samples of the signal to be encrypted. Each sample is operated on by a key or function to produce modified signal samples, and the modified signal samples are summed or combined to produce the encrypted signal. According to one aspect of the invention, at least one of the keys or functions includes a nonlinear function. In some embodiments, the functions are time-variant for improved security. Decryption is accomplished in some embodiments by an equalizer. The preferred equalizer is the maximum-likelihood-sequence estimators matched to the encryption functions. A Viterbi algorithm makes it easy to implement the matched equalizer.

Abstract: In a first aspect of the invention, method for classifying characters within a character string entered via a keyboard device includes logging interrupts, checking a time between interrupts, checking an interrupt duration and classifying the characters within the character string based upon the time between interrupts and the interrupt duration. In a second aspect of the invention, a method for protecting against timing attacks against a trusted path mechanism includes employing a multithreaded process with a first thread to prevent any timing Trojan horses from running, running the first thread in a loop at a first priority and preventing unprivileged processes from obtaining a priority higher than the first priority.