METHOD FOR TRANSMITTING DIGITAL INFORMATION IN COMPUTER NETWORK Russian patent published in 2004 - IPC

FIELD: electrical communications and computer engineering including methods and devices for cryptographic data processing. SUBSTANCE: method includes following procedures on sending end: input signal division into n-bit blocks; generation of protection key in the form of k-bit binary vector; its supply for initial fill-up of k-bit feedback shift register that generates maximal-length pseudorandom sequence incorporating 2^k-1 binary characters; generation of pseudorandom-sequence binary vector by concurrently taking information off different bits of shift register, length of pseudorandom-sequence binary vector being chosen to equal that of input-signal binary-vector block; coding of input signal block by modulo two addition of pseudorandom-sequence binary vector bits to binary-vector bits of input signal block followed by transfer of encoded input signal block over communication line; on receiving end: signal reception; generation of protection key in the form of k-bit binary vector; its supply for initial fill-up of k-bit feedback shift register; its supply for initial fill-up of k-bit feedback shift register; generation of n-bit pseudorandom-sequence binary vector like on sending end; decoding of encoded input-signal block by modulo two addition of its bits to pseudorandom-sequence binary vector bits; transfer of input signal to terminal device. Novelty is that on sending end second pseudorandom-sequence binary vector is generated by concurrently taking information off other different n bits of shift register and conversion of encoded input-signal block by modulo P = 2ⁿ addition (this number corresponding to binary vector of input-signal block) to number corresponding to second binary vector of pseudorandom sequence and that on receiving end second binary vector of pseudorandom sequence is generated like on sending end, converted into joint binary vector by subtracting number corresponding to second pseudorandom-sequence binary vector from number P, and encoded input-signal block is recovered by modulo P addition (this number corresponding to joint pseudorandom-sequence binary vector) to number corresponding to binary vector of encoded input- signal block. EFFECT: enhanced code stability to attacks basing on known and selected source texts. 1 cl, 2 dwg