sibley@psuvax.UUCP (06/25/83)
Sam Wagstaff was here at Penn State yesterday and gave a very interesting seminar on how to break the RSA cryptosystem. I suppose people who really follow these things already know about this, but I hadn't realized just how much progress had been made on this problem. He described some (not all) of the algorithms involved and then described a machine that he and others had built which factors 50 digit integers in about an hour. It can factor 70 digit integers in a month -- apparently they actually did it. Most surprising is that the machine only cost $6000. They have funds for an even better second generation version. He claimed that it would be possible to factor 100 digit numbers in a month with such a machine. However, they won't build a machine with quite that capacity since some 100-digit RSA systems are actually being used. Even so, the second version will be a lot more expensive. Does this mean the end of RSA as a serious system? He didn't say, but he did claim that keys much larger than 100 digits entail encryption and decryption rates which might be too slow for a high-volume operation. You could, of course, keep both the encryption and decryption processes secret. You wouldn't have a public-key system any more, but you wouldn't have to worry about anyone factoring your key either. Dave Sibley ...psuvax!sibley