[fc-discuss] Financial Cryptography Update: RSA keys - crunchable at 1024?

[iang@iang.org]

((((( Financial Cryptography Update: RSA keys - crunchable at 1024? )))))

                           September 14, 2005


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https://www.financialcryptography.com/mt/archives/000551.html



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New factoring hardware designs suggest that 1024 bit numbers can be
factored for $1 million.  *That's significant* - that brings ordinary
keys into the reach of ordinary agencies.

If so, that means most intelligence agencies can probably already
crunch most common key sizes.  It still means that the capability is
likely limited to intelligence agencies, which is some comfort for many
of us, but not of comfort if you happen to live in a country where
civil liberties are not well respected and keys and data are considered
to be "on loan" to citizens - you be the judge on that call.

Either way, with SHA1 also suffering badly at the hands of the Shandong
marauders, it puts DSA into critical territory - not expected to
survive even given emergency surgery and definately no longer
Pareto-complete.  For RSA keys, jump them up to 2048 or 4096 if you can
afford the CPU,

Here's the source of info, posted by Steve Bellovin.

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Open to the Public
								       
	
DATE:	 TODAY * TODAY * TODAY * WEDNESDAY, Sept. 14 2005
TIME:	 4:00 p.m. - 5:30 p.m.
PLACE:	 32-G575, Stata Center, 32 Vassar Street
TITLE:	 Special-Purpose Hardware for Integer Factoring
SPEAKER: Eran Tromer, Weizmann Institute
								       
	
Factoring of large integers is of considerable interest in
cryptography and algorithmic number theory. In the quest for
factorization of larger integers, the present bottleneck lies in the
sieving and matrix steps of the Number Field Sieve algorithm. In a
series of works, several special-purpose hardware architectures for
these steps were proposed and evaluated.
								       
	
The use of custom hardware, as opposed to the traditional RAM model,
offers major benefits (beyond plain reduction of overheads): the
possibility of vast fine-grained parallelism, and the chance to
identify and exploit technological tradeoffs at the algorithmic level.
								       
	
Taken together, these works have reduced the cost of factoring by many
orders of magnitude, making it feasible, for example, to factor
1024-bit integers within one year at the cost of about US$1M (as
opposed to the trillions of US$ forecasted previously). This talk will
survey these results, emphasizing the underlying general ideas.
								       
	
Joint works with Adi Shamir, Arjen Lenstra, Willi Geiselmann, Rainer
Steinwandt, Hubert K?pfer, Jim Tomlinson, Wil Kortsmit, Bruce Dodson,
James Hughes and Paul Leyland.
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Some other notes:

http://www.keylength.com/index.php
http://citeseer.ist.psu.edu/287428.html

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