RSA-640 factored

One of the RSA challenge numbers, RSA-640, has been factored:

RSA-640 = 3107418240490043721350750035888567930037346022842727545720161948823
       2064405180815045563468296717232867824379162728380334154710731085019
       19548529007337724822783525742386454014691736602477652346609

Factor 1: 1634733645809253848443133883865090859841783670033092312181110852389
       333100104508151212118167511579

Factor 2: 1900871281664822113126851573935413975471896789968515493666638539088
       027103802104498957191261465571

The number, which carries a US$ 20,000 prize for its solution, was factored by F. Bahr, M. Boehm, J. Franke and T. Kleinjung using GFNS. The computation took 5 months on eighty 2.2 GHz Opteron CPUs.

RSA-640 is not the largest challenge number to be factored so far -- RSA-200 is larger (despite the confusing name, RSA-200 is 663 bits long, compared to RSA-640, which is 640 bits). RSA-200 was factored in May 2005 by the same team.

Tags: Cryptography, RSA, RSA-640