Abstract: Blind signature systems secure against chosen message attack are disclosed. Multiple candidate original messages can be accommodated. Each of plural candidates in the final signature can be marked by the party issuing the signature in a way that is unmodifiable by the party receiving the signatures. The exponents on the candidates in the final signature need not be predictable by either party. In some embodiments, these exponents are not at all or are only partly determined by the candidates in the signature shown. Single candidate signatures are also accommodated.

Abstract: Data transmission to an aircraft is secured by encrypting the data between a remote data source and the aircraft. The encryption is initiated when a random number is coupled to the remote location where it is encoded with the data in accordance with a preselected encryption sequence. The encoded data, after transmission to the aircraft, is decoded in the same sequence so that the original data may be retrieved.

Abstract: An inductive coupling permits bi-directional data and power to be transferred through the skin of an aircraft thereby avoiding pin connectors. The coupling comprises a sending unit which is detachably mounted to the skin exterior, and the pick-up unit is located on the interior skin surface in alignment with the sending unit.

Abstract: An integrated circuit (IC) card is provided with an external memory having a much larger memory capacity than that of a usual internal memory packaged inside the IC card together with a processor. The external memory can be managed only by the processor through an external IC card accepted by a terminal machine.

Abstract: Apparatus and a method are disclosed to enable on-line modification and upgrading of terminal software in a communication network while maintaining the integrity of communication between a service provider and a subscriber using the network. Software is downloaded on a booter channel on the communication network. A subscriber terminal, coupled to the network initiates a communication with the network to receive downloaded booter data. The downloaded data is stored, and a checksum is computed from at least a portion of the downloaded data. The checksum is tested for validity, and control of the subscriber terminal is released to the downloaded software only if the checksum is valid.

Abstract: The plasma generating apparatus and method of this invention is particularly, although not exclusively, suitable for plasma spraying. The plasma spray apparatus and method of this invention generates a free-standing electromagnetically coalesced stable plasma through which feedstock may be fed, eliminating problems with conventional radial feed plasma guns. The plasma spray apparatus of this invention includes a plurality of pilot plasma guns preferably angularly displaced symmetrically about a common axis and a main transfer electrode located downstream of the pilot plasma guns having a nozzle bore coaxially aligned with the common axis. The plasmas generated by the pilot plasma guns are directed into the throat of the main transfer electrode bore and a second plasma gas is supplied to the throat of the main transfer electrode bore which is ionized and coalesced with the plasmas generated by the pilot plasma guns, generating a free-standing electromagnetically coalesced plasma.

Abstract: An integrated I/O interface for a communication terminal, connectable with an external analog communication device and with an external digital communication device, includes an I/O interface subsystem having analog and digital arrays, a first connector for connecting the I/O interface subsystem to a digital processor for the terminal, and a second connector for connecting the I/O interface subsystem to both the analog communication device and the digital communication device. The digital array and the analog array including a CODEC are mounted on a platform carrier on the I/O interface subsystem board. The second connector is a single connector having pins for transmitting the analog signals, pins for the digital signals, a pin indicating whether the analog or digital mode is selected, and a pin indicating which external communication device is selected. The second connector also has common EMI and EMP protective filter circuits incorporated therein to protect the I/O interface subsystem.

Abstract: There are provided an encipher method of enciphering message data made by a microcomputer or the like at a high speed by using encipher keys which have previously been stored in a smart card or the like and a decipher method of deciphering the ciphertext made by the encipher method at a high speed by using the encipher keys. The encipher method and the decipher method are suitable for, particularly, a 32-bit microcomputer and include a process expressed by the function Rot.sub.2 i(x) (i=2, 3, 4) in each process. Rot.sub.2 i(x) is the process to circular shift a data train x of 32 bits to the left or right by 2.sup.i bits (i=2, 3, 4).

Abstract: An apparatus for the protection of signal copy for prevention unauthorized copying of music software such as records, compact discs and music tape by recording is arranged such that when recording audio signals on a medium, certain supplemental information is added to the audio signal to be recorded, and in the process of copying by reproducing this medium, when the supplemental signal is detected in the reproduced signal, the copying action is stopped to protect it from being copied.

Abstract: A monolithic microwave integrated circuit (MMIC) phase shifter is implemented in push-pull configuration with the quadrant selection and vector modulation functions combined. These functions are provided by four sets of adjustable gate-width dual-gate FETs and a pair of lumped element filter networks with a relative differential phase shift of 90.degree..

Abstract: In an electronic cash implementing method, a user makes a bank apply a blind signature to user information Vi produced, by a one-way function, from secret information Si containing identification information, thereby obtaining signed user information. Further, the user makes the bank apply a blind signature to information containing authentication information Xi produced, by a one-way function, from random information Ri, thereby obtaining signed authentication information. The user uses an information group containing the signed user information, the signed authentication information, the user information and the authentication information, as electronic cash for payment to a shop. The shop verifies the validity of the signed user information and the signed authentication information, and produces and sends to the user an inquiry. In response to the inquiry the user produces a response Yi by using secret information and random information and sends it to the shop.

Abstract: A method of data communication, particularly for long data messages, is disclosed. The data code words of a message are arranged in segments, each with its own header, and are assigned message and segment identification. A receiver reconstructs the data message segment by segment and, in the non-group call situation, transmits an acknowledgement after the receipt of a segment. The receiver comprises a resettable timer which is set on the receipt of an acceptable segment and runs for a pre-determined duration. If another segment is received within the duration of the timer and has the same identification as the acceptable segment, then it is treated as a retransmission. Efficiency of the data communication method can be increased by retransmitted data code words being included with new data code words in a segment rather than being transmitted in a separate segment requiring its own header. Optionally, an efficient form of bit interleaving may be used.

Abstract: A data communication apparatus comprises: means for dividing data to be transmitted into a plurality of blocks and extracting the data from each block; a first multi-layered neural network of three or more layers which has weighting coefficients to output the same data as the input data for the data extracted from each block and which can output data from an intermediate layer; the transmission data extracted from each block being inputted to the first neural network and outputted from the intermediate layer; means for encoding the transmission data which is outputted from the intermediate layer of the first neural network and, thereafter, transmitting; means for receiving and decoding the transmitted data; a second multi-layered neural network of three or more layers which has the same weight coefficients as those of the first neural network and can input data from an intermediate layer; the decoded data of each block being inputted to the second neural network and outputted from an output layer; and means f

Abstract: A soft logic cryptographic circuit that can be reprogrammed with various cipher algorithms. The cryptographic circuit can be manufactured in a non-secure environment because a security sensitive cipher algorithm can be programmed after the manufacturing process.

Abstract: The encoder/decoder comprises a spherical body on which is provided a plurality of different letters and/or numerals. Connecting means in the form of three circular members sharing the same axis encompass the sphere, two defining two parallel sighting hoops and the third defining a sighting ring. The connecting means are mounted on a support body so that the relative rotation of the connecting means and the body can be effected. In use, the body is rotated until two specified indicia lie usually between the two sighting hoops in a specified order. Then, one or more indicia are read from the sighting ring. The encoder/decoder may be used to protect computer software against copying, and may also be used to hinder unauthorized access to remote computer systems. Thus, the number of individuals using a system can be limited to the number interrogating the user, can determine whether he has in his possession a suitable encoder/decoder such as outlined above.

Abstract: A GPS receiver apparatus retrieves a maximum correlation point between a PN code involved in a satellite signal and a generated PN code with use of n detecting means each concurrently processing the retrieval operation to acquire the PN code of the satellite signal. The apparatus acquires the PN code of the satellite signal, unless said maximum correlation is yielded, by effecting a correlation processing or taking the synchronization among phases of the PN code in which the generated PN code is shifted in its phase by n/2 bits to retrieve the maximum correlation point. The apparatus further tracks GPS radiowaves with the use of a plurality of said detecting means which has been used to acquire the PN code.

Abstract: A fully digital phase-locked loop comprises a sampler (1), an analog-to-digital converter (2), two quadrature demodulators (3 and 4) and their associated filters (5 and 6), and a decision logic (7) effecting the correction of the sampling phase around the value of the free-running frequency (f.sub.e) by the addition or subtraction of machine cycles of a signal processor (9).

Abstract: According to the invention, the keyboard consists of a matrix of keys and variable visible indicia. Each of the variable visible indicia is associated with a key. Upon each keystroke on the keyboard, the system randomly changes the positions of all of the indicia on the matrix. Because the true value of any particular key is independent of the value displayed on the variable visible indicia, a casual observer can not learn the keystrokes being entered into the keyboard. If the code entered at the keyboard matches a stored value, the user is granted access.

Abstract: A network includes digital computers, resources such as disk drives, printers and modems or disk files, file records or tasks, and a communications channel permitting data transfer between each digital computer and the resources. The function of mediating conflicting demands for network resources is distributed among the digital computers. A file server or other storage device connected to the communications channel contains an access log. Each digital computer accesses a required resource by first recording an entry in the access log identifying the required resource and then scanning the access log to locate any conflicting entry identifying the same resource. The access procedure is terminated if the conflicting entry is located and the recorded entry is then deleted. The digital computer otherwise accesses the required resource and deletes the recorded entry once use of the resource has terminated.

Abstract: An active multichannel video processing hub which provides optinum transition from fiber to coaxial cable, provides optimum trading of bandwidth for signal to noise ratio. Fiber optic links have a very large bandwidth capability. Larger distances can be covered with fiber optic links without repeaters. This offers not only saving in maintenance, but has no radiation and offers bidirectional capabilities not easily achievable with coax-based trunks. Scrambled signals are transmitted over the fiber and converted to VSB-AM signals at the hub for transmission over the coaxial portion of the trunk. This keeps the bulky and complex headend scrambling equipment in one central location instead of spreading it over many hub locations. The inherent heterodyne processing capabilities of the hub permit it to link headends with different frequency plans. Also, the hub-based trunk does not obsolete existing equipment and method of operation.