From: Barry Sperling <barry@...>
Date: 2004-08-28T06:07:31+09:00
Subject: ASCII, RSA AND BIGNUM

Continuing on the track of the previous question about ASCII, I'm using 
each_byte to change a string to ASCII for the purpose of encrypting it, 
using the theory of the RSA algorithm ( to see if I can! ).  Part of 
this algorithm requires getting a power ( a**b ) in which the "a" is the 
ASCII value of the string and the "b" is some large number that is 
dictated by the RSA algorithm ( about 25,000,000,000,000 for my test 
string ).  However, when I do this I get the error

NaN
test_ascii.rbw:20: warning: in a**b, b may be too big

While I could simulate a power with a loop, doing this 25 trillion times 
might take a little while.  I could also simulate the power with logs, 
but I'm sure that this would add inaccuracies and the integral number 
has to be exact.  Is there a way out or is this just a fundamental 
limitation of Bignums in Ruby?
Barry