Abstract: The invention is a scrambler apparatus for scrambling a character block, in particular for cryptographic applications, which apparatus comprises a scrambler module (210) adapted for transforming a first character block (220a) consisting of first character components (225a) to a scrambled second character block (220b) consisting of second character components (225b), configured with a scrambler automaton (250), and each second character component (225b) is determined based on a first character component (225a) of the first character block (220a) having the position corresponding to the position of the given second character component (225b), at least one character component (225a, 225b) from the available character components (225a, 225b) of the first character block (220a) and the second character block (220b), and a single input signal character component (225c) of the input signal character block (220c). The invention is, furthermore, a scrambling method, a descrambler apparatus and a descrambling method.

Abstract: The subject of the invention is a symmetric key stream cipher cryptographic method for encrypting plaintexts and decrypting ciphertexts during which process a text to be encrypted or an encrypted text is scanned with an input/output data buffer (5), a pseudo random number is created with a pseudo random number generator (8) with a seed (12), a key automaton (11) is used for encryption and/or decryption. It is characterized in that the procedure involves the method whereby using the characters of the text scanned by the input/output data buffer (5) and the pseudo random number generated by the pseudo random number generator (8), an element of the key automaton's (11) transition matrix is directly reached from the input/output data buffer (5); the procedure is then repeated. A symmetric key stream cipher cryptographic device for implementing the method of claim 1 is also the subject of the invention.

Abstract: The subject of the invention is a symmetric key stream cipher cryptographic method for encrypting plaintexts and decrypting ciphertexts during which process a text to be encrypted or an encrypted text is scanned with an input/output data buffer (5), a pseudo random number is created with a pseudo random number generator (8) with a seed (12), a key automaton (11) is used for encryption and/or decryption. It is characterized in that the procedure involves the method whereby using the characters of the text scanned by the input/output data buffer (5) and the pseudo random number generated by the pseudo random number generator (8), an element of the key automaton's (11) transition matrix is directly reached from the input/output data buffer (5); the procedure is then repeated. A symmetric key stream cipher cryptographic device for implementing the method of claim 1 is also the subject of the invention.

Abstract: The invention is, firstly, a cryptographic apparatus for encrypting unencrypted data, comprising an input module for inputting the unencrypted data and an output module for outputting encrypted data, and a key automaton (44) adapted for converting the unencrypted data into the encrypted data, and the key automaton (44) is an composition of automata said composition of automata having a set of states and a set of input signals identical to each other and being implemented as a permutation automaton without output signals, said composition of automata comprises at least one factor automaton without output signals, each of the unencrypted data and the encrypted data has a character set identical to each other, and the set of states and the set of input signals, respectively, consist of blocks obtained from all possible combinations of said character set, wherein the blocks are of a predetermined block length. The invention is, furthermore, a cryptographic apparatus for decrypting encrypted data.

Abstract: The invention is, firstly, a cryptographic apparatus for encrypting unencrypted data, comprising an input module for inputting the unencrypted data and an output module for outputting encrypted data, and a key automaton (44) adapted for converting the unencrypted data into the encrypted data, and the key automaton (44) is an composition of automata said composition of automata having a set of states and a set of input signals identical to each other and being implemented as a permutation automaton without output signals, said composition of automata comprises at least one factor automaton without output signals, each of the unencrypted data and the encrypted data has a character set identical to each other, and the set of states and the set of input signals, respectively, consist of blocks obtained from all possible combinations of said character set, wherein the blocks are of a predetermined block length. The invention is, furthermore, a cryptographic apparatus for decrypting encrypted data.

Abstract: For information encryption and decryption the apparatus uses the same hardware keys, which have the transition matrix of a key-automaton with no output signal and with an initial state and a final state burnt in. To each character in the character set of the plaintext message there is one or more final states of the key-automaton assigned. During encryption the message is read in sequentially character by character and the key automaton assigns to each character a random character string, whose length is adjustable length within a given length range. The process is the following: for each character in the message the apparatus generates a character string of adjustable length and with no initial- and end markers, which takes the apparatus from its current state into the final state that corresponds to the subsequent character of the message. The apparatus creates the encrypted message by linking these character strings together. The encrypted message can be decrypted using the same apparatus.