Abstract: A method of creating an encryption system for encrypting a plurality of plaintext words is provided. The method comprises associating (104) respective plaintext words (202) with respective sets (207) of error positions (212) of an error vector, and associating (106) respective values of at least one of the plaintext words (202) with respective error vector values, wherein positions of the respective error vector values outside the set (207) of error positions associated with the one of the plaintext words (202) are zero. The method further comprises associating (108) the respective values of the plaintext word (202) with respective representations of respective syndromes (218) of the respective error vectors according to an error correcting code.

Abstract: A method of creating an encryption system for encrypting a plurality of plaintext words is provided. The method comprises associating (104) respective plaintext words (202) with respective sets (207) of error positions (212) of an error vector, and associating (106) respective values of at least one of the plaintext words (202) with respective error vector values, wherein positions of the respective error vector values outside the set (207) of error positions associated with the one of the plaintext words (202) are zero. The method further comprises associating (108) the respective values of the plaintext word (202) with respective representations of respective syndromes (218) of the respective error vectors according to an error correcting code.

Abstract: An encrypting exponentiation modulo M is effected by a modular multiplication X*YmodM, where M is a temporally steady but instance-wise non-uniform modulus. The method involves an iterative series of steps. Each step executes one or two first multiplications to produce a first result, and a trim-down reduction of the size of the first result by one or more second multiplications to produce a second result. The method furthermore takes a distinctive measure for keeping the final result of each step below a predetermined multiplicity of the modulus. In particular, the method postpones substantially any subtraction of the modulus as pertaining to the measure to a terminal phase of the modular exponentiation. This is possible through choosing in an appropriate manner one or more parameters figuring in the method. This further maintains overall temporal performance.

Abstract: A digital information signal is channel encoded into a channel signal. Data sequences in the channel encoded information signal that give rise to an analog signal, upon reproduction or reception, with a single frequency component at f.sub.b M, are limited in length. M being an integer constant larger than 2 and f.sub.b being the bit frequency in the channel encoded information signal.

Abstract: A circuit arrangement calculates pseudo-random permutations of a set of numbers. Including compositions of some basic pseudo-random permutations and the inverse permutations of permutations that are calculated. The basic pseudo-random permutations, their compositions and inverses are all calculated by the same generator whose operation is commanded to calculate the appropriate permutation by specifying a set of integer coefficients f.sub.i. The generator calculates the permutations .sigma.(n) of the numbers n=0 . . . m-1 corresponding to ##EQU1## where .alpha. is an integer number which is divisible by all prime factors of m and by four if m is divisible by four, with a potency s(.alpha.) of two or higher. When the same a is used for all permutations it is assured that all compositions and inverses of the generated permutations can be calculated in the same way, by the same generator.

Abstract: In a presentation system a transmitter station transmits messages that provide information on demand. Such message is divided into parts. An earlier part of the message is presented more often than at least one later part of the messages. In particular, the presentation pattern is such that upon accessing the message's firts parts all other parts can be contiguously accessed according to a standard presentation velocity as from a time instant that is within a prespecified distance in time from the start of accessing said first part. In particular, the distance may be zero.

Abstract: A coupling network for a data processor is described, including, one or more cross bar switches having inputs and outputs and one or more arrays of silos. A series connection is formed in which these components are alternately arranged in a succession having at least three elements. A retrocoupling network is used for coupling outputs of a data processor to its inputs, and it also provides external communication. The configuration offers ample freedom of mapping, notably in cyclostatic processors.

Abstract: There is described the calculation of a multiplicatively inverted element of an input vector specified in a finite major Galois field. From the set of vector coefficients there is formed a first set of linear forms and a further set of matrix-organized linear forms. The elements of the first set of linear forms are pairwise combined to quadratic forms that represent a set of coefficients of a vector defined in a subfield in the major field. This latter vector is then converted to its multiplicative inverse, after which the inverted subfield-vector has its coefficients multiplied by elements of the further set to generate the multiplicative inverse in the major field. By scrupulously combining the generation of various intermediate terms a further reduction of the necessary hardware and/or processing time is attained.