Greg Miller wrote:
> DES is, shall we say, demanding... A small block of text can take an hour on a
> PC XT, until you finish the optimization. I'm afraid to think what it'd be
> like on a 6502... BTW: The C128 runs at 2MHz
You may be thinking of RSA encryption. RSA involves arithmetic of huge
integers, and can even take several seconds on a fast RISC chip to do one
decryption using a large key. RSA allows the sharing of messages securely
between people without having to exchange keys in secret.
DES, on the other hand, is just the shuffling of bits for several rounds
on a 64 bit block, based on the value of the 56 bit key, which must be
passed secretly between parties to be secure.
Intel made DES-on-a-chip a long time ago,and it was obvious they were
just selling an 8051 masked with the DES code. 8051's are what PC XT's
use as the *keyboard* microcontroller. As I recall, it ran at a few
hundred blocks per second, totally acceptable and in line with my
estimate of what the Atari 2600 can do. DES on a good RISC chip can
encrypt several hundred *thousand* blocks per second.
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