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Random numbers

    It has lately been discussed different ways to construct pure
random number generators by means of radiactive decay. I must admit
that this is a very good way to produce such numbers, but for a
number of reasons it is impractical to use such a device. (High
radiation levels are needed too produce a significant amount of data.)

    What I have been thinking of is a way to reduce the amount pure
random data needed to produce good random sequences. The way to do
this would too have a weak random number generator like:
R(n+1)=(17*R(n)+1)mod256, and then inject the pure random into this
function giving the result R(n+1)=(17*R(n)+1+PR(t))mod256 or
something of the like.

    Would this constitute a sufficiently secure stream of data for
use in one time pads? Has this been thought of before ?


    A friend of mine now serving in the air force gave me a report of
the cryptographic devices used for communicating on permanent lines.
(Twisted pair or something dug down). The machines used till now are
huge totaly outdated mostly mechanical monsters. While not
transmitting data the machines produce random data to hinder traffic
analysys (like how many messages are sent), these data are produced
by cookiebox sized thing, and I strongly suspect it to be of a very
mechanical nature. Thats how a came up with the idea of a very
inexpensive way to produce random data by mechanical means: Use a
contaner filled with marbles some made of conducting, and some of non-
conducting material. Then mix them in some way or another (this is
bound to make a lot of noise) and in the container there should be a
few closely placed points of contact that would be able to send a
small current through a steel ball if it where to pass over the pair
of contacts, and what do we have: Random Data ! (I know this is not
very practical at all)