1. Generator for generating binary ciphering sequences, comprising: a first random generator generated binary pseudo random sequences at at least one data output, wherein said first random generator has a clock input being connected to an external clock generator and wherein applying a clocking signal to the clock input has the effect of producing a new binary state at the at least one data output of said first random generator; function generator means being provided at the at least one data output of said first random generator and performing predetermined logic operations on said data output; a pair of further random generators generating binary pseudo random sequences at at least one data output, wherein said further random generators in each case have a clock input and wherein applying a clocking signal to the clock input has in each case the effect of producing a new binary state at the at least one data output of said further random generators; wherein the clock input of each of said further random generators is connected to the output of one of said function generator means with the effect, that said further random generators in each case produce their new binary state at random times; and at least one combining unit for logically combining the binary states being available at random times at the data outputs of said further random generators, wherein said combining unit performs a predetermined logical combining function to form at least one ciphering sequence so that both binary states are assumed with approximately the same frequency when the arguments of said combining function pass through all possible values; wherein the sequence generated by said first random generator and the sequences generated by said further random generators fulfill the following relations: (a) the period k of the sequence generated by said first random generator divides one of the two periods M, M of the sequences generated by said pair of further random generators, (b) the sums over the binary values of the sequences generated by said pair of further random generators, taken over a period k of the sequence of said first random generator are defined by F=2.sup.e +p(M) and F=2.sup.e +p(M) respectively, where e and e are positive integral numbers and p(M) and p(M) are arbitrary polynominals in M and M.