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Old 2020-11-18, 12:53   #4
Dr Sardonicus
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Feb 2017

2·3·719 Posts

Originally Posted by VBCurtis View Post
256-bit inputs are small, and YAFU will run the quadratic sieve to factor them. This method is faster for inputs below about 100 decimal digits, but the time to factor scales more steeply than the Number Field Sieve (NFS).
384 bits is well above that 100 digits, so YAFU is running NFS.
What you see on screen is the output of the first phase of NFS algorithm- polynomial selection. That phase will run for roughly 5% of the total factorization time. Sieving takes 80-85% of the total time, and the linear algebra takes 10-15% at the end.

A 384-bit input on a desktop quad-core should take a couple hours to factor. Difficulty doubles every 5 decimal digits or so, so a 512-bit number will take 5-10 days (depending on the speed of your hardware).

The performance info above should be pasted into any FAQ or README file that's supposed to tell would-be users what to expect.
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