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RSA-576 Factorization Officially Announced

product byproduct writes "RSA Security finally has a news item about the December 2003 factorization of RSA-576. (See earlier Slashdot coverage). We now know what the computational cost was: the 174-digit number was factored "using approximately 100 workstations in a little more than three months"."

40 of 141 comments (clear)

  1. Lots of hardware... by basil+montreal · · Score: 5, Insightful

    That's a ton of computer hardware to use on factoring... I wonder why they didn't just use a distributed system (like seti@home) to do this... at least it's free.

    1. Re:Lots of hardware... by ezzzD55J · · Score: 5, Interesting

      Because it's difficult to efficiently parallelize (distribute) the factorisation algorithm, especially the final step which so far has always happened on 1 machine. In fact, if you can paralellize the final step of the GNFS (general number field sieve is generally used for these factorisations), you have yourself a PhD. thesis (in math and/or CS), I remember reading in sci.crypt.

    2. Re:Lots of hardware... by Chilliwilli · · Score: 3, Insightful

      I'm sorry but factorisation problems and SETI really infuriate me. Firstly we can calculate how long something will take to compute with ease using simple the simple CS complexity analysis we all learnt at university.. then theres the SETI people.. not that I don't want to know whether there's life on other planets but to be honest there is so much we don't understand on our own planet that could have far greater reward for us all. Things I'm talking about might be research into climate, new fuels, medicines. The only distributed task I contribute to is folding@home because all others don't seem worth the extra energy and heat my PC will put out.

      --
      Cure cancer.. and stuff! www.team45.info
  2. Re:It has to be asked... by Sheetrock · · Score: 2, Interesting
    Especially in light of all the projects one could be donating computer cycles to, such as protein folding or SETI.

    What does this tell us? That if you throw enough machines and/or money at a solvable cryptographic challenge you'll solve it?

    --

    Try not. Do or do not, there is no try.
    -- Dr. Spock, stardate 2822-3.




  3. Still safe for a while by BuddieFox · · Score: 5, Interesting

    We should still be reasonably safe using the RSA-algorithm for a while more since the number is the equivalent of a 576-bit key. Most cryptography programs support upto 4096-bit keys, and the strength of a key increases exponentially for every bit if my memory does not fail me (correct me if it does).

    Safe, that is unless someone invents quantum computers and makes them easy to produce.. :)

    1. Re:Still safe for a while by Ckwop · · Score: 5, Interesting

      Also remember the moore's law doesn't apply to factoring algorithms.. This is because for the GNFS the *memory* speed is what's important and that isn't growing nearly as quickly..

      Not convinced? Look at the linear proportionality in this graph

      Simon.

    2. Re:Still safe for a while by Ckwop · · Score: 4, Informative

      Wow nice random word generator.. Can I have a go?

      Seriosuly, It's utter rubbish. I mean please explain to me how you stack an S-box into a corner of a cryptographic chamber..

      It's just a substitution you muppet.. And cryptography isn't all hardware speed.. I mean WEP

      was broken with trivial computing power!

      Simon.

    3. Re:Still safe for a while by thedanc · · Score: 5, Informative

      Bear in mind, using bits to exponentially increase cryptographic strength only works until you reach the Berenstein factor, which is a practical limit on the number of S-boxes that can be stacked in any particular corner of the cryptographic chamber. After a certain point, which varies according to the chamber ceiling, it is possible albiet less space efficient to take advantage of parallel stacking to some extent.

      Mods -- how could you let this get modded up? First, S-boxes are in DES, not RSA. Next, even if the random reference was to the correct cryptographic algorithm, the rest of the comment still makes no sense at all.

      C'mon people, post if you have a clue, and only if you have a clue.

    4. Re:Still safe for a while by cortana · · Score: 2, Insightful

      For each specific algorithm, the progress follows Moore's law that states that the speed of computers double every 18 months.

      Sorry for sounding like a dick, but Moore's Law states that the number of transistors per unit area doubles every eighteen months. This does not directly correspond to an increase in computer "speed".

    5. Re:Still safe for a while by dmaxwell · · Score: 2, Interesting

      The rules are different for public key cryptography. You are correct in that every bit added to a symmetric crypto key doubles the keyspace. In public key crypto which RSA is one type of, it is necessary to add 10 bits to double the difficulty. That 10 bit number is somewhat fuzzy. It can be a little more or a little less depending on whether we are talking about elliptic curves or Diffie-Hellman and others.

    6. Re:Still safe for a while by andalay · · Score: 2, Interesting

      WEP had a flaw in the protocol.

      The flaw made it possible to inject unauthorized packets and reduce the time/space needed for brute forcing the key.

      Thanks for demonstrating a common misconception in cryptography: it is all about encryption and decryption. Its not. Its also about the algorithms and protocols you use in your applications. Encryption/decryption is a factor in the security but it is not the whole point of cryptography.

      As a result, when people break SSL,WEP, it is as much a part of practical cryptography as factoring integers

  4. Re:It has to be asked... by lewko · · Score: 4, Insightful

    No.

    It tells us HOW MANY machines we need to throw at the challenge.

    The whole key to protecting information is to make it cost more to recover the information than it is worth.

    For example, if information is going to need to be kept secret for twenty years, projects like this help you learn based on current technology, how much crypto is sufficent (or overkill).

    --
    Do you or your partner snore? - Visit www.snoring.com.au
  5. Security by nuclear305 · · Score: 5, Insightful

    Of course, the whole idea behind key strength is rather moot if the user gets careless with his keys/passphrase.

    Unfortunately, crypto is only as strong as the user(weakest link)

    While it's not always comforting to know these things can be factored, at least we can take comfort in knowing that *most* hackers/spooks don't exactly have a 100 node server farm laying around just dying to crack your keys.

    Of course, unless you're the NSA and measure their servers by acres...

    1. Re:Security by CoolGopher · · Score: 4, Interesting
      we can take comfort in knowing that *most* hackers/spooks don't exactly have a 100 node server farm laying around just dying to crack your keys.

      Of course, unless you're the NSA and measure their servers by acres...

      Or if you grabbed the source for the latest windoze worm and modded it to bruteforce keys in addition to spreading...

      I have a suspicion that doing that would give you a supercomputer that quite possibly ranked #1 on the supercomputer charts, and for free to boot*.

      *) Comes with complimentary government provided lodging and meals.

    2. Re:Security by ConsumedByTV · · Score: 2, Informative

      While I agree with the sentiment of this remark, I have to disagree with some implementations.

      Yes, it's not going to be difficult to attack the users passphrase if it's stupid. However you make an assumption that most people who encrypt their harddrive keep their keys on the laptop.

      I don't.

      With loop-aes, you have pretty good abstraction.

      So you can have a set of gpg keys, a file encrypted to a given public key, and the data to be decrypted, all in different places.

      In theory, it can be done over a network, a usb keychain, a serial cable, whatever you want.

      In the end, if they have all three, yes, the password is the last link obviously.

      The key is to make sure that those three aren't in the same place at the same time, once the system is on, the keys are loaded into memory and aren't needed. Remove the usb key with your gpg secret key. Remove the usb key or detach from the server that has the actual encrypted gpg file that holds the actual disk encryption keys.

      You need all three to attack the users password at that point. Assuming that you decide it's not worth cracking the gpg encrypted file (4096bit), that it's not worth cracking the passphrase (war and peace in leet speak), you can attack the disk file itself.

      Each encrypted partition has 64 different keys that are all
      61 different characters long.
      Example:
      kd11Zki1oKre4iSwXaMX+C/wH+t7RXBtG 3Q0rog5pYAHHVm0tb CWDYp0MgII

      So yea, it's possible to crack that, but I highly doubt that you will.

      So stealing my laptop takes away my hardware, and my encrypted disks. It doesn't mean you have an easy way into my data.

      Check out the loop-aes project for practical examples of this in Gnu/Linux.

      It's not perfect, but it's better than the stupid cryptoloop crap where you can't ever change your password because that requires writing all the data to the disk again (with the new key).

      --


      "Not my manner of thinking but the manner of thinking of others has been the source of my unhappiness." - M
  6. More about distributed computing... by BillGodfrey · · Score: 3, Informative
  7. The advantage of one way encryption... by MosesJones · · Score: 3, Funny


    I encrypt everything on my hard-drive using one-way compact encryption, it only cost me $100 and converts every file into 0 bytes that can't be de-crypted by anyone... not even me. Now THAT is proper security.

    I previously used 2^(10e20) bit encryption which would have taken several universes to crack. Unfortunately it took one earth life to encrypt a 1 Mb file so I had to revert to the super-secure method above.

    And Yes I do have a tin-foil hat... why do you ask ? Oh and the application that does the one way encryption. Well I work on Windows but I get this Unix utility called Cygwin and the guy sold me a program that does the encryption. I had a look at what was in encrypt.sh and what it says is

    cat /dev/null > $1

    Amazing how simple UNIX makes encryption... but then I use Windows so its all beyond me.

    --
    An Eye for an Eye will make the whole world blind - Gandhi
  8. Hundred computers * 3 months by Gopal.V · · Score: 5, Interesting

    That makes it 240000 computer hours ... too cheap .. Think about this :

    "Toy Story 2" had about 800,000 computer hours worth of rendering.
    "The Hulk" had 2.5 Million computer hours
    My office has nearly 400 fast machines , imagine this running them makes it 25 days . Running that every weekend makes it 12 weeks or 3 months ... It's a weekend job if I can sneak this in as along with the next upgrade.

    DDoS time is over with all networks being careful about... the next big windows worm will be a distributed processing program :)

    1. Re:Hundred computers * 3 months by duffbeer703 · · Score: 3, Interesting

      Think about the commercial application of cyrpto... would anyone invest Pixars IT budget to steal a few credit card numbers?

      Even with military-style secrets, timing is key. If a US war plan is intercepted by a foreign intelligence service, only to be decrypted months later, that data is pretty useless.

      --
      Conformity is the jailer of freedom and enemy of growth. -JFK
    2. Re:Hundred computers * 3 months by Short+Circuit · · Score: 2, Interesting

      would anyone invest Pixars IT budget to steal a few credit card numbers?

      It depends on the credit limits of the cards, and whether or not the holder knows the data's been accessed..

    3. Re:Hundred computers * 3 months by phoenix.bam! · · Score: 2, Interesting

      I'd imagine intelligence agencies would have a lot mroe than 100 machines working on cracking the US military plans...

  9. 40 Licks by thpdg · · Score: 3, Funny

    It begs the question, how many workstations, for how many months, would it take to find out
    How many licks does it take to get to the center of a Tootsie Pop?
    I'm afraid the world will never know.

    --

    -Patrick

    "They never stop thinking about new ways to harm our country and our people, and neither do we."

    1. Re:40 Licks by Anonymous Coward · · Score: 2, Funny

      Theh-Ree.

  10. If anyone wants... by Phidoux · · Score: 3, Informative

    ... to waste 3 months and 100 computers trying to read my RSA-576 encrypted information, they are welcome

  11. Re:Factoring in advance by RupW · · Score: 3, Insightful

    If you knew that factoring big numbers was important to breaking encryption, and would be for quite a long time wouldn't you simply have started a huge factoring effort decades ago? I know I would have.

    Factoring what? You won't know the number you need factored until you intercept or steal the encrypted data.

    You could, I suppose, start multiplying every pair of primes together and try and organise a database of the results but the storage - even if you just store some sort of clue to the primes used - would be staggering, even for just 1024-bit RSA.

  12. Re:It has to be asked... by RupW · · Score: 3, Insightful

    Surely a complexity calculation would suffice? After running a few iterations of the solver

    Because there's no motive to optimise the solver. Open up the project, offer a prize and you'll get many eyes looking for the absolute best solution - then you can study the complexity of that.

  13. Re:Factoring in advance by RupW · · Score: 2, Informative

    Not true, because if you can factorise the modulus in the public key (which is generally easy to get), you can generate the private key.

    Yeah, that was misleading - I was just trying to say you need a target for your arbitrary factor effort. In my mind I'd figured you'd have to have the encrypted message to know what private key it was encrypted for - although I realise now that's not necessarily true (and neither's the reverse). But it could be for real tinfoil-hat types :-)

    There's no good reason, either, why a public key can't be kept as confidential as a private key or a symmetric cipher key - it's just that once you publish it to a few people there are more points of failure. And if you don't have the public key (in GPG's implementation at least) you don't have anything to try and factorise because it's not bundled with the encrypted data.

  14. Re:Factoring in advance by tadmas · · Score: 5, Insightful

    You won't know the number you need factored until you intercept or steal the encrypted data.

    You don't have to steal anything. The number to factor (the modulus) is given away as part of the public key.

    organise a database of the results but the storage - even if you just store some sort of clue to the primes used - would be staggering, even for just 1024-bit RSA.

    For 1024-bit numbers, the factors will be on the order of 512-bits. The density of primes is rougly 1/ln(n), and ln(2^512) is about 355, so you should expect around every 355 numbers to be prime. That's only 3e151 numbers, not to mention that you'd have to figure every product of the two, which is 0.5*(3e151)^2, or 7e302 numbers.

    Staggering doesn't begin to describe how many of these things you'd have to store.

  15. Why waste all the CPU power? by tangent3 · · Score: 4, Funny

    There's a far easier way to crack the the key

  16. Re:Virginia Tech by Chexum · · Score: 3, Insightful

    Uh, oh, someone is bad at math...

    I don't think VA's unknown numbered G5 park is about 2^448th more powerful than 100 PC(?) nodes. I don't think it's possible.

    Or, I simply have been trolled :)

    On the other hand, let me check my sig again...

    --
    "Ten years from now, they could do it in a few seconds." -- The Racketeer of the Hellfire Club, 1993, Phrack 42
  17. Anyone know what the predicted strenght was? by pmcevoy · · Score: 3, Interesting

    Does anyone know what the predicted lifetime of the 576 bit key was?

    I mean, when they say that we should be using 4096bit keys today, how long do they predict that it will take to crack that key? (taking into account Moores law and perhaps linear growth over time of the number of clients contributing CPU cycles). Is it possible to guestimate?

  18. Jens Franke by greppling · · Score: 5, Interesting
    (As far as I understand, he and Thorsten Kleinjung wrote most of the software used, and did most of the work in the project, while the other institutions were rather donating computing time.)

    I happen to know him a little, as one of my friends is his student, and another one was. If you think mathematicians are crazy, Franke is more than that. When you talk to him, he will usually just continue to stare at the piece of paper he has directly in front of his eyes (Nobody knows why he isn't wearing glasses.) and think of that as a normal way of communicating. His office consists of 3 huge desks (plus a computer desk); on each of them there is huge bunch of completely unorganized papers lying around, mixed with empty yoghurt cans.

    His mathematical skill is enormous, he has done research in quite a lot of different areas of mathematics (analysis, algebraic geometry, algebraic topology, category theory), but he never bothers at all with making his results well-known. (In fact, at least one time he actually had to be persuaded to even publish his result, which got immediately accepted in Inventionaes, the most highly regarded journal in pure mathematics.) He even couldn't be bothered to apply for a much better-payed position at another university in Germany when he was almost urged to do so.

    Anyone who knows him will burst out laughing when he reads that he supposedly said "I'm very proud of all these individuals from around the world and their efforts to solve this first factoring challenge." and all this other stuff in that paragraph of the article. I bet the author of this press release desperately tried to get some phrases longer than 5 words out of his mouth, gave up, and then decided to just make up all the quotes.

    Now with his mathematical skills, number factoring is (in his own opinion) a rather dull activity. The reason he is doing this is that he expects an economic breakdown soon, and he thinks of his knowledge in number-factoring as an assurance against the coming job crisis. (Of course, his position is guaranteed by the German state until his retirement.)

    But if you manage to get along with him, he is actually quite nice and extremely helpful.

    1. Re:Jens Franke by Xilman · · Score: 2, Interesting
      I happen to know him a little, as one of my friends is his student, and another one was. If you think mathematicians are crazy, Franke is more than that. When you talk to him, he will usually just continue to stare at the piece of paper he has directly in front of his eyes (Nobody knows why he isn't wearing glasses.) and think of that as a normal way of communicating.

      I also know Jens quite well (we are on first-name terms) and he seems sane enough to me. Perhaps I have hung around with mathematicians too much!

      But if you manage to get along with him, he is actually quite nice and extremely helpful.

      Seconded. Thorsten Kleinjung is also one of the good guys and very helpful.

      Paul

      --
      Lasciate ogne speranza, voi ch'intrate
  19. Next Time, Hire Google by VernonNemitz · · Score: 3, Interesting

    They say that Google is preparing an IPO, but sometimes I wonder what they need the money for. They already had enough money for 10,000-100,000 servers, after all. If they doubled or quintupled that acreage of computer-farm, would your search-results come to you down the Internet pipe so much faster that you'd be glad the did?

    And they had the money to hire the experts needed to manage that cluster like a single supercomputer. Sure, they probably got some of that initial funding from ordinary venture capitalists, but what if some Govt. outfit helped, on the grounds of requesting access for occasional factoring purposes? After that IPO gets invested in a bigger farm, not even 2048-bit keys may be safe.

  20. soooo.... by MasTRE · · Score: 2, Insightful

    It took longer for them to come up with the press release than it did for their code to be broken. Lookin' good, RSA!

    --
    Must-not-watch TV!
  21. Re:It has to be asked... by StarfishOne · · Score: 2, Insightful
    IMHO projects like Folding@Home, TSC, United Devices, Lifemapper or ClimatePrediction.net are far more important then breaking a piece of encrypted material.

    Like RC5 for example. If you break the RC5-64 key, everyone is happy. Then they want to break the RC-72 key.

    Wow.. it takes ages and ages.. and what does it *really* proof?

    Yes, it is breakable too.. wow. I'd rather have a few new medicins available, thank you :)

    What I'm trying to say: there is plenty of computer power available on this world.. but not nearly near enough! There are far more important and interesting things to do with it then breaking some non-sense line of text!

  22. Re:So, has any Slashdot reader checked the results by Ant2 · · Score: 2, Informative

    Yes. They are correct.

    BigInteger p1 = new BigInteger("39807508642406493739712550055038649119 9064362342526708406385189575946388957261768583317" );
    BigInteger p2 = new BigInteger("47277214610743530253622307197304822463 2914695302097116459852171130520711256363590397527" );
    BigInteger p = p1.multiply(p2);
    System.out.println(p);

    188198812920607963838697239461650439807163563379 41 73827007633564229888597152346654853190606065047430 45317388011303396716199692321205734031879550656996 221305168759307650257059

  23. Memory speed vs. CPU speed increases by billstewart · · Score: 4, Interesting
    You missed his point, though perhaps he could have expressed it more clearly. Many applications are CPU-bound, some are memory-size-bound, some are memory-speed-bound.
    • CPU speed has been doubling pretty fast, every 1.5-2 years.
    • Memory size (or at least, size/price ratio) has been growing pretty fast.
    • Disk capacity has been booming faster than CPU speed, though disk seek times have been changing much more slowly.
    • Memory speed has been lagging - I forget the exact numbers, but some of the hashcash folks did some research and found the speed doubled every N years, maybe 3-4. Certainly not the same curve as CPU speed.
    If the real constraint in GNFS is storing and retrieving data, not multiplication speed, then you could easily get an environment where memory speed increases are the gating factor for your Moore's Law growth, no CPU speed increases, so your K-bit key is good for 2-3 times as many years as you'd expect.

    On the other hand, factoring is a problem where the increases in Algorithm Speed have been just as critical as increases in Computer Speed. So maybe GNFS has reached the point where it's computer-speed-bound, but next year's Super-Duper-Number-Field-Sieve may be several times more efficient than GNFS, just like GNFS was several times more efficient than NFS in the ranges that are now interesting. Sometimes this happens just because mathematicians keep doing new work, and sometimes it happens because computer capacity (e.g. memory size) grows enough from Moore's Law that algorithms which weren't practical in the past become practical. There were factoring tools that weren't useful when most computers had 128MB of RAM, but work fine now, and there may be tools that aren't practical when most computers have less than 4GB of RAM, but five years from now your SonyNintendo box will have enough RAM to run Sieve@Home.

    --

    Bill Stewart
    New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
  24. See also dmaxwell's correction by Beryllium+Sphere(tm) · · Score: 2, Informative

    >Most cryptography programs support upto 4096-bit keys, and the strength of a key increases exponentially for every bit if my memory does not fail me (correct me if it does).

    First, adding one bit to the size of a number only doubles the range of possible numbers.

    Second, even that doesn't apply to RSA because not every number is a possible key (not even close!). A key is the product of two large primes. Numbers like that are thin on the ground.

    Third, there's no value in making your crypto harder to crack until you've made the rest of your system as secure as your crypto. Ask yourself which is cheaper -- brute-forcing a DES key, or breaking into your home and training a hidden camera on your screen?

  25. Goes to show by BCW2 · · Score: 2, Insightful

    That any key can be cracked if enough computing power is thrown at it. Remember NSA does this as their job, now how many keys have been cracked? All or real close to it.

    --
    Professional Politicians are not the solution, they ARE the problem.