FIELD: information technology.
SUBSTANCE: invention relates to encoding and decoding data stream. Message encoder, suitable for implementing a method for encoding a data stream to transmit said data by means of an encoded stream, in which coding is a result of comparing data stream to a second data stream, formed by a pseudorandom sequence means of an exclusive comparison operation (XOR), wherein generation of pseudorandom sequence is performed by a method for generation of a pseudorandom sequence, performing following steps: a) providing a differential equation with initial value x'=f(x, t), b) providing initial value for a differential equation x0=x(t0), c) providing an integration step δt for differential equation for time discretisation tk=t0+k⋅δt, k=1, 2, 3, …, d) performing numerical integration of differential equation of initial value and with step δt to obtain approximation to solution xk=x(tk), e) generating a first sequence of values by means of sampling values of xk, presented in numerical form with floating point in form 0,d0d1d2d3d4...dr...dw⋅10e, where e is exponent, w is length of mantissa, d0 is most representative digit of mantissa and dr -certain digit, such that it and all digits to its left of approximation to solution xk coincide with exact value of solution of differential equation, f) generating pseudorandom sequence with digits di...dr from a selection of sequence of values xk wherein i is a predetermined integer value verifying 0<i≤r, g) pseudorandom sequence expands into a sequence with a large number of elements in accordance with following steps, of: predetermining a positive integer value DIM, constructing two vectors V1 and V2 of integers with dimension DIM from pseudorandom sequence, constructing an expansion matrix Me with dimension DIM⋅DIM from product V1⋅V2T, where V2T is transposed vector V2, generating expanded sequence by concatenating rows of matrix Me.
EFFECT: technical result is effective protection of data stream.
15 cl, 4 dwg, 1 tbl
