# [rc5] Let's factor RSA-155!

Mike Marcelais michmarc at MICROSOFT.com
Fri Oct 24 11:58:02 EDT 1997

```> At 02:24 PM 10/24/97 +0200, you wrote:
> >> The largest number which has ever been factored is RSA-130. It's
> been
> >> estimated that RSA-155 (10^25 times larger!) could be factored in
> >> 500,000 MIPS years using the quadratic seive (QS) method, and
> >> about 17,000 MIPS years (if I remember correctly), using the
> >> General Number Field Seive (GNFS) method.
> 	Could someone enlighten me -- what's a MIPS year? I mean, how
> does that
> compare to "real" time?
>
MIPS = million instructions per second.  A MIPS-Year is the amount of
work done if you do a million instructions per second (a MIPS) for an
entire year.  Since there are 60*60*24*365.25 = 31557600 seconds  in an
average year, this is about 3e13 (3 times 10-to-the-13th) instructions.

To translate this into "real time" you need to know how fast your
machine works.  For example, well optimized code on a Pentium 200 can
execute 400 MIPS.  This means that it would take 78,894 seconds to do a
MIPS-Year worth of work, or about 21 hours.

+------------------------+----------------------+
| Mike Marcelais         | MS Office Developer  |
| michmarc at microsoft.com | and Magic Rules Guru |
+------------------------+----------------------+
| Opinions expressed in this post are mine, and |
| do not necessarily reflect those of Microsoft |
+--= Moonstone Dragon =---------------= UDIC =--+

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