Large Primes

[Neil McEvoy]

> >  If, for the sake of simple argument, we say that the
> > probability (P) of a successful attack on either type of cipher is about
> the
> > same then, by arranging the work of the two ciphers in the current
> fashion,
> > the engineer increases the probability of a successful attack to P/2
where
> P
> > is less than unity.
>
>    ... successful attack to 2P ...   :-)
>
>    Brian
>
>
approximately, where P is small. In general though,

1 - (1-P)**2

Neil