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Old 2012-04-06, 23:11   #23
Stargate38
 
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I figured out that it has about the same difficulty as a GNFS 250-270. That's almost 27 times as hard as RSA-768. Is that correct or did I miscalculate?
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Old 2012-04-06, 23:36   #24
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I figured out that it has about the same difficulty as a GNFS 250-270. That's almost 27 times as hard as RSA-768. Is that correct or did I miscalculate?
The latter.
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Old 2012-04-07, 00:00   #25
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Oh! Where did I mess up?
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Old 2012-04-07, 01:03   #26
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Oh! Where did I mess up?
I think it's the fact that if PARI lead me correctly it has 320 digits not 270.
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Old 2012-04-07, 01:12   #27
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I was saying how easy a SNFS320 is compared to a GNFS232 like RSA-768. They differ by 88 digits, yet the difficulty ratio is only about 81. I hope that is correct. I don't know how to calculate the SNFS factoring time, given only the difficulty in digits. I do know that there is a factor of about 3 for a 10-digit increase when using GNFS.

Last fiddled with by Stargate38 on 2012-04-07 at 01:14
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Old 2012-04-07, 01:22   #28
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Originally Posted by Stargate38 View Post
I was saying how easy a SNFS320 is compared to a GNFS232 like RSA-768. They differ by 88 digits, yet the difficulty ratio is only about 81. I hope that is correct. I don't know how to calculate the SNFS factoring time, given only the difficulty in digits. I do know that there is a factor of about 3 for a 10-digit increase when using GNFS.
yeah that means being off by 50 digits = 3^5 = 81*3 = 243 times as hard as you thought.
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Old 2012-04-07, 01:28   #29
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I know with GNFS the factoring time is 3 times bigger with every 10 digits, but what is the rate for SNFS? Is it the same?
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Old 2012-04-07, 01:29   #30
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I know with GNFS the factoring time is 3 times bigger with every 10 digits, but what is the rate for SNFS? Is it the same?
that I don't know because I only know what the letters mean.
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Old 2012-04-07, 01:54   #31
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I hope I got this right. I used the factor of 3 per 10-digit increase rule for GNFS:

Using GNFS, RSA-1024 would take 3((308-100)/10)*5 hours on a dual core and RSA-2048 would take 3((617-100)/10)*5 hours, which is ~1229277376184679090360 years. I hope quantum computers come quick or we may be waiting for 1.2 sextillion years for the factors of RSA-2048. In comparison, RSA 1024 would take ~1990173 years. That means a lot when you compare it with RSA-768. I read that 232 digits take about 3000 CPU years, but I ended up with 1820 CPU years.

Last fiddled with by Stargate38 on 2012-04-07 at 01:58
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Old 2012-04-07, 02:11   #32
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I know with GNFS the factoring time is 3 times bigger with every 10 digits, but what is the rate for SNFS? Is it the same?
Does the term "sub-exponential growth" mean anything to you? -bdodson
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Old 2012-04-07, 05:33   #33
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Does the term "sub-exponential growth" mean anything to you? -bdodson
Oh, be nice. It's useful to approximate the time needed for factoring by piecewise exponentials.

Quote:
Originally Posted by Stargate38 View Post
I know with GNFS the factoring time is 3 times bigger with every 10 digits, but what is the rate for SNFS? Is it the same?
GNFS has that behavior around 195-205 digits by the standard formula (setting o(1) = 0, which is a bit generous); using the same in the SNFS formula gives a factor of 2.4 rather than 3. SNFS is, in general, somewhat less sensitive to the size of the number than GNFS (though obviously both depend on it).
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