I have written two Ada driven ciphers that are complete and have been tweaked for the last time.

I have used an early Ada compiler - a Gnat311.p - of about 1995 vintage  <= Ada-95.

In order that the ciphers can run in 32-bit computers which are still going to be around for some time despite the availability of the 64-bit operating system in Windows 8.1 which I also use, I have had to put a bound on the maximum integer size output of computations at 2^31 which of course is the maximum positive integer that 32-bit computers can handle.

Running the same software that was written for 32-bit computers in the  64-bit environment of 8.1 and raising the bar on integer size I thought I should be able to do this ok but no - the cipher will still crash if the integer size is greater than 2^31 when I thought I could go up to 2^63.

As it happens this is not a problem crypto wise because the cipher is independent of the integer size but I am intrigued that this overflow should still happen.

I am coming to the conclusion that the max integer size than can be used without integer overflow occurring in any computer is a function of the Ada compiler being used and not the computer operating system???

Could anybody throw some light on this conjecture?

Thanking you in anticipation of your usual help,

adacrypt