Comment How many do you think NSA will buy? (Score 5) 123
But seriously, this was an interesting article. It just goes to prove that if you are using key sizes of less than 512 bits for public key cryptosystems, you may be vulnerable to advances in factoring rather than advances in raw processor speed.
The main advantage of this is that 512 bit keys can be factored in 9-10 weeks as opposed to 6-7 months with the previous application of this factoring method (described in the paper). This means that with this equipment and assuming that the estimate is correct, 768 bit keys can be factored in 1038 years (Shamir's estimate of 6000 * len(512)). A 1024 bit key would be factorable in approximately 1x10^6 years with this method and optimal conditions, however such a number requires exhorbitant space, upwards of 256 GBytes for the sieve 10 TeraBytes to store its matrices.
Bottom line, any key of 512 bits is good for about 9-10 weeks. The recommended minimum key size is still 1024 bits. The paper's conclusion sums this up best:
Conclusion The idea presented by Dr. Shamir is a nice theoretical advance, but until it can be implemented and the matrix difficulties resolved it will not be a threat to even 768-bit RSA keys, let alone 1024.Its more important to have the freedom to use strong encryption so that we don't have to worry about being forced to choose weak keys in order to communicate.
