DES was a procedure whereby data were passed through a series of eight S-boxes, actually mathematical operations, that when combined with a unique user key converted it into what appeared to be alphanumeric garbage. The receiver also had a copy of the key, which could be used in combination with the same set of mathematical operations to convert it back.
He knew that back when DES was being invented by IBM, the National Security Agency had purposely sabotaged Big Blue's original plan to make it uncrackable. NSA had insisted that the key, a string of zeroes and ones, be limited to 56 bits, rather than the proposed 128 bits, which would have made the system so complex it would have been safe forever. The reason, of course, was that NSA didn't want an unbreakable cipher loose on the planet; after all, their primary business was reading other people's mail. IBM didn't know it at the time, but the smaller key was already a pushover for NSA's Cray supercomputers, which could try a trillion random keys per second and routinely crack any 56-bit DES encryption in the world in half a day.
Anybody familiar with the intelligence business was well aware of that. Which was, obviously, why somebody had turned to NSA.
But Eva said she'd tried the usual random-key procedure and got nowhere. So what was the answer?
His head was buzzing from the raki now, but he kept turning over in his mind the possibility that she'd been looking in the wrong place. Trying to find the DES key when in fact this encryption used some entirely different scheme.
He rubbed at his temples and tried to run the scenario backward.
Project Daedalus. The more he thought about it, the more . . .
"Zeno." He looked up from the screen. "Do you still have that copy of Realm of the Spirit?" He'd sent the old Greek an autographed first edition the week it came out.
"Your book, Michael? Of course I have it. I treasure it. It's in the bedroom, in back."
"Mind getting it for me? I feel like a little light reading."