Method of generating a pseudo-random sequence of signs of a large sequence length

Claim 1

Apparatus for generating a pseudo-random sequence of digital bits which constitute a message key for encrypting a message, such apparatus comprising: a first memory for storing a series of N preselected prime numbers; a second memory for storing a series of N random characters; arithmetic means connected to said first and second memories for generating N subsequences of bits, the first of such subsequences being generated by adding a first of said random characters to a first of said prime numbers, each jth (j≦N) of such subsequences being generated by adding the jth of said random characters to the product of the jth of said series of prime numbers multiplied by: (i) a predetermined first factor when the (j-1)th subsequence is less than a predetermined value; (ii) a predetermined second factor when the (j-1)th subsequence is equal to or greater than said predetermined value; a register coupled to said arithmetic means for storing each of the subsequences generated thereby; and counter means connected to said register and to each of said first and second memories for reading out therefrom the jth random character and the jth prime number to said arithmetic means in response to storage of the (j-1)th subsequence in said register; the content of said register after storage of all N subsequences therein constituting said message key.