Re: Anyone seen the 'quantum cryptanalysis' thread on sci.crypt?
Tim May:
In any case, the Shor work on a quantum factorer is interesting, but is at least several decades away, in my opinion. And even then it is likely to be "workable" out to some number of digits (roughly, number of digits = precision needed), by which time the conventional advances in computer power will mean we're all using 10,000-bit moduli (especially if we have just heard that NSA has just spend $32 billion to build a Shor machine able to factor 3000-bit moduli :-} ).
I won't argue whether Shor's work will be implemented or not within any given time period, but I thought that one of the most important properties of it is that once (and if) achieved, the resources required to factor increasingly large moduli lengths go up only polynomially, not exponentially. Doug Cutrell
Doug Cutrell wrote:
I won't argue whether Shor's work will be implemented or not within any given time period, but I thought that one of the most important properties of it is that once (and if) achieved, the resources required to factor increasingly large moduli lengths go up only polynomially, not exponentially.
I don't know. I skimmed Shor's stuff when it appeared. A lot more analysis will be needed....and we have many decades left to get started! But even if the effort required grows polynomially, think of what that means in real dollars, potentially. For example, just to imagine some engineering numbers: Alice is spending 15 cents worth of 2045 computer power to use a 10,000-bit modulus for her messages. The GSA (Global Security Agency, which replaced the NSA in 2008) has a Shor machine, built with the latest nanotech rod-logic computers. It cost them $32 billion to build, and it can "crack" a 10,000-bit modulus in 10 days, at a cost of $20,000 (in 2045 dollars). Alice switches to 15,000-bit moduli....the how much longer does it take the Shor machine to do its thing? (Even if polynomial, what factor?) I won't speculate further. The numbers are indeterminate, even to Shor, I suspect. In any case, nothing for Cypherpunks to worry about in our lifetimes (certainly not in my lifetime, and probably not in the lifetime of our youngest members). --Tim May -- .......................................................................... Timothy C. May | Crypto Anarchy: encryption, digital money, tcmay@netcom.com | anonymous networks, digital pseudonyms, zero 408-688-5409 | knowledge, reputations, information markets, W.A.S.T.E.: Aptos, CA | black markets, collapse of governments. Higher Power: 2^859433 | Public Key: PGP and MailSafe available. Cypherpunks list: majordomo@toad.com with body message of only: subscribe cypherpunks. FAQ available at ftp.netcom.com in pub/tcmay
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