Re: Encryption on the AS/400

From: Nathan M. Andelin <nandelin@relational-data.com>
> > If I simply wanted to encrypt data on my local machine
> > I could knock up a program in about an hour that would
> > give me 100% uncrackable encryption. Simply use a
> > random key the same length as the data to be protected.
> > XOR each byte of the message with the corresponding
> > byte of the key.
>
> It seems to me that the hard part with this method is generating /
> maintaining a truely random key that is the same length as your data.  What
> if you need to encrypt large files?
>

work with 16 byte values.
set x0 = some random seed value
xor each block of 16 bytes with xi
where xi = fractional part of a*log(xj)
where j = i-1 and a is some (relatively) large value e.g. 1234.5678

this gives you a pseudo-random number with no period
(within the accuracy of 16 bytes).