Go Back > Fun Stuff > Lounge

Thread Tools
Old 2007-09-16, 21:00   #1
Bemusing Prompter
ixfd64's Avatar
Dec 2002

22·607 Posts
Default something wrong here?

New Scientist recently published an article about quantum computing, entitled "Qubits poised to reveal our secrets" (I didn't use the New Scientist official site since it requires a subscription).

However, somewhere in the article, it says:

For instance, to find the prime factors of a 10-digit public key, approximately 100,000 calculations are needed; for a 50-digit number about 10 trillion trillion are required. IBM’s Blue Gene supercomputer would take a fraction of a second to crack a 10-digit key, but about 100 years for a 50-digit key. And keys are now much longer than 50 digits. In 1994, mathematician Peter Shor at Bell Labs in New Jersey developed a routine that radically reduces the time required to make those calculations. There was just one rather large catch: it could only run on a computer that exploits quantum mechanics.
Huh? I think there must have been a mistake or something, as people have factored 200-digit numbers.

Last fiddled with by ixfd64 on 2007-09-16 at 21:01
ixfd64 is offline   Reply With Quote
Old 2007-09-17, 00:16   #2
rogue's Avatar
Apr 2003
Between here and the

23×809 Posts

It states that Blue Gene would take that long, but I assume that they are referring to a brute force method.
rogue is offline   Reply With Quote
Old 2007-09-17, 13:20   #3
Account Deleted
Mini-Geek's Avatar
"Tim Sorbera"
Aug 2006
San Antonio, TX USA

2·5·7·61 Posts

Originally Posted by ixfd64 View Post
Huh? I think there must have been a mistake or something, as people have factored 200-digit numbers.
I was going to write about how the key they're talking about likely has many more than 10 possible combinations per digit, but then I realized that even a 256 digit key with 50 possible combinations is in the 400-digit range, and wouldn't be so hard to factor, not 100 years of Blue Gene at least, even if semiprime.
So...I think I agree with you that there is a mistake there.

EDIT: I just had my (quite old and slow) computer factor a 51 digit semiprime number, and it did it in 1 minute 34 seconds, with me doing other things on the computer. So, in any case, it's definitely not talking about a semiprime that's about 10^50.

Last fiddled with by Mini-Geek on 2007-09-17 at 13:55
Mini-Geek is offline   Reply With Quote

Thread Tools

Similar Threads
Thread Thread Starter Forum Replies Last Post
Is Moore's Law wrong, or is it wrong-headed (6th time around) jasong jasong 12 2016-05-27 11:01
what I do wrong pepi37 Linux 4 2015-07-12 09:13
Am I doing it wrong? kracker PrimeNet 3 2012-07-01 22:35
something wrong with my RAM? ixfd64 Hardware 13 2010-07-17 20:49
Something is very wrong... RhymeBomb Information & Answers 7 2010-02-28 09:53

All times are UTC. The time now is 07:09.

Thu Dec 9 07:09:57 UTC 2021 up 139 days, 1:38, 0 users, load averages: 1.39, 1.25, 1.23

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.

This forum has received and complied with 0 (zero) government requests for information.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation.
A copy of the license is included in the FAQ.