## The Clock Is Ticking On Encryption 228

Posted
by
timothy

from the promise-that-keeps-on-giving dept.

from the promise-that-keeps-on-giving dept.

CWmike writes

*"In the indictment that led to the expulsion of ten Russian spies from the US in the summer of 2010, the FBI said that it gained access to their communications after surreptitiously entering one of the spies' homes, during which agents found a piece of paper with a 27-character password. The FBI had found it more productive to burglarize a house than to crack a 216-bit code, despite having the computational resources of the US government behind it, writes Lamont Wood. That's because modern cryptography, when used correctly, is rock solid. Cracking an encrypted message can require time frames that dwarf the age of the universe. That's the case today. 'The entire commercial world runs off the assumption that encryption is rock solid and is not breakable,' says Joe Moorcones, vice president of information security firm SafeNet. But within the foreseeable future, cracking those same codes could become trivial, thanks to quantum computing."*
## The U.S. government is VERY corrupt. (Score:2, Insightful)

The FBI had found it more productive to burglarize a house...That kind of behavior, burglarizing houses, committing a crime to stop other crimes, is destructive to the rest of the nation. There are mistakes. There are agents who use their power to cause trouble. There are many other negative consequences, such as the FBI agents acting to support their personal ideas of political action, which has happened numerous times in the past.

## Re:The U.S. government is VERY corrupt. (Score:5, Insightful)

That kind of behavior, burglarizing houses, committing a crime to stop other crimes, is destructive to the rest of the nation.

I don't find it such a bad thing, if they have a warrant from a non-corrupt judicial system.

You can hardly say fighting espionage is inherently corrupt.

## Re: (Score:2)

That kind of behavior, burglarizing houses, committing a crime to stop other crimes, is destructive to the rest of the nation.

I don't find it such a bad thing, if they have a warrant from a non-corrupt judicial system.

You can hardly say fighting espionage is inherently corrupt.

True enough, but a government that increasingly finds it necessary to hide it's actions in that arena from even the tacit judicial oversight now in place deserves every bit of the suspicion it suffers, and then some. History has (or should have) taught us well that the excuse that "we're protecting you from " is almost always a sign of bad things to come.

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Will I be charged with capital murder of a federal agent for shooting the armed burglar that I find in my house? Or will it be a perfectly legal response like it would be if the burglar was a regular citizen.

## Re:The U.S. government is VERY corrupt. (Score:5, Insightful)

I rather think that the FBI is quite careful to check that you are not in the house before they go in. They probably have someone trailing you who will warn them if you start heading home or if they lose track of where you are. They are not idiots and have no interest in getting into a firefight unnecessarily.

Basically, stop being stupid. The FBI is not going round breaking into people's houses willy-nilly. They entered those specific houses because they had probable cause to believe that their occupants were hostile agents of a foreign power engaged in illegal espionage, and they had acquired warrants to do so, supported by oath and particularly describing the places to be searched and the things to be seized. Are you seriously complaining because government agents

obeyed the Constitution to the letterin the course of exercising their duty to uphold the rule of law?! I can scarcely believe that any American would display such contempt for the principles on which your hard-won freedom is founded.## Re: (Score:2)

I can scarcely believe that any American would display such contempt for the principles on which your hard-won freedom is founded.

You must not know many Americans.

## Re: (Score:2)

You would be charged with murder. Shooting at policemen is a bad idea, whatever the scenario.

The agents, although technically violating some law or policy, were acting in good faith in pursuit of justice.

## Re: (Score:3)

The expectation is that there will be a witness to the 4th ammendment specified exception. Whether or not you're told, well that's where wiretapping (and keylogging etc) come into play, i'm not certain of any precident in this area but I'd imagine there has to have been a few that made it to trial.

## The FBI has vigilantes (Score:4, Interesting)

And they'll break any law to accomplish the mission. The FBI has murderers and serial killers who are confidential informants. They also have thieves who are confidential informants.

It's a surprise to me that some Russian spies who you'd expect would be trained to deal with counter intelligence would be so careless.

## the word is burgle (Score:2)

To burglarize a house is to turn the house into a burglar - I don't think that's what the FBI did, whatever they said they did.

I'm willing to believe the house was burgled - that seems more usual nefarious behaviour --- yes - a word with all the vowels in

## Re: (Score:3)

## More like Slashdot is VERY bad at journalism (Score:2)

And loves to editorialize shit to try and spin things. Burglary is illegally entering someone's house for the purpose of theft. Now the important part there is "illegally" and also what the intent is. If I enter your house, because you gave me a key and want me to watch you cat, that is legal. Well guess what? It is also legal for the police to search your house, if they get a warrant which the FBI did. Further they can get warrants for surveillance of various types like tapping your phones or planting bugs

## Re: (Score:2)

burglarizing housesCounter-espionage actions against foreigners who you know to be spies working for another country ain't the same as burglary. Of course you know that, you trolling twit.

## Re: (Score:2)

xkcd is never obligatory. Form your own opinions and speak for yourself rather than simply agreeing with another individual.

## Re: (Score:2)

In fact, I'd wager to say dozens of people have replied to Obligatory xkcd comments with more or less ex

## Is "quantum computing" the next "cloud computing"? (Score:3, Insightful)

Many of us have known it for a long time, but more and more people are waking up to the fact that "cloud computing" is a sham. It's basically 1970s-era mainframe computing revived and renamed, with a layer after layer of marketing bullshit layered on. It has all of the same drawbacks as mainframe computing plus some, and often without many of the benefits.

"Quantum computing" risks becoming the next such mania. Soon enough, some marketing dipshits will come along and relabel some lousy existing technology as "quantum computing" (even when it absolutely isn't). This will get the press going, and soon the buzz will be overwhelming. Every manufacturer will be hard at work putting "Quantum Powered" stickers on the hardware they sell, and all sorts of software providers will be labeling their software as "quantum-compatible".

If it's anything like cloud computing has been, it'll just be a waste of time and money.

## Re: (Score:3)

Yep. There's a *very* limited set of tasks that quantum computing can be used for. Factoring numbers just happens to be one of them, that's why it's always dragged out in articles about quantum computing.

To be more specific, a problem needs these properties for a quantum computer to be useful:

1. The only way to solve it is to guess answers repeatedly and check them,

2. There are n possible answers to check,

3. Every possible answer takes the same amount of time to check, and

4.

## Quite right (Score:5, Insightful)

Wait, who didn't know this already? The title is misleading, but the fact that quantum computing breaks RSA is pretty standard knowledge (among people who have heard of quantum computing at all, I guess). Of course, there are other encryption schemes that seem to work just fine (e.g. Elliptic curve cryptography) with quantum computing, and there's not much evidence that algorithms other than RSA are broken. Note: factoring isn't NP-complete! So far there's no reason to believe it's not an "easy" problem, except that we haven't figured out how to do it. More intersetingly, there's a lot of research being done on quantum cryptography [wikipedia.org], which is really quite cool. In total, quantum computing should probably give us more security than it breaks, except for the idiots who keep using outdated algorithms long after they're broken, but they'd be screwed anyway.

So, the sky is falling! Oh wait, no, that's just the weather changing.

## Re: (Score:3)

but the fact that quantum computing breaks RSA is pretty standard knowledge (among people who have heard of quantum computing)

Yep - and given how well it's currently working, you're screwed if you're using 4-bit RSA (to steal a famous quote from Schneier).

We've been hearing this story for long enough that the 'quantum computing breaks crypto' crowd ought to stop broadcasting that claim until they can break keys of arbitrary length.

## Re: (Score:2)

It's important for some people. No encryption is unbreakable, when you encrypt you always have to decide how long the information needs to be secret for. It may not still be the case (computing power is a lot cheaper now), but fighter aircraft used to use very weak encryption for their communications, because it was only important that it remain uncracked by a determined adversary for a few hours and adding more latency was more dangerous than someone learning what you said a couple of hours ago. In cont

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## Re: (Score:2)

A minor nit: any "hard" problem that's harder one way than the other will ultimately be attackable via quantum methods. This is true for almost any public key system including ECC. There hasn't been as much work quantum vs ECC, but only because ECC is pretty cutting edge.

the source of all human knowledge [wikipedia.org] has a couple links to research on the topic.

It is certainly the case that you can overcome quantum attacks by using quantum crypto, but that's going to be a problem for people who have less money t

## Re: (Score:2)

A minor nit: any "hard" problem that's harder one way than the other will ultimately be attackable via quantum methods.

Can you point me toward more information on this? I haven't heard anything like that before -- all arguments I've seen that say quantum computing breaks cryptographic schemes are just based on Shor's algorithm, which I didn't think had such broad implications. (I didn't know it breaks ECC, too.)

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Obviously you didn't RTFA, which states EC cryptography is just as easily breakable via quantum computation (moreso, in fact, than RSA). The upshot: use QKD to transmit the key, then rely on classical encryption schemes (e.g. AES) for the message (for which QKD is nearly useless). Actually, it sounds perfect since QKD is generally considered unbreakable. Then again, computing power increases so quickly that I doubt AES will be secure for long.

wow, I actually learned something FTFA.

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MUSThave direct fiber optic links for it to work.## Re: (Score:2)

If they get quantum computers to work at a useful scale, they'll be near useless for communication (both because they're so expensive and because of the networking problems you mentioned), but will be great for breaking all the encryption that everyone else uses around the world. In short, we need a classical cryptography scheme that's still secure with quantum computing.

## Re: (Score:2)

Yes, this is definitely a valid point. However, QKD is right now at a level pretty far past quantum computation, so maybe there's hope that QKD will be widespread enough for normal users before quantum computation reaches the point where it can break heavy RSA encryption. I envision some sort of routing hub that can accept keys via QKD which then passes it securely to the client.

However, if QKD can't be managed for long distances (that is, if we don't find a good way to send it over long distances OR if we

## Re: (Score:2)

## Cost/benefit (Score:2)

The title is misleading, but the fact that quantum computing breaks RSA is pretty standard knowledgeYeah, but even if they knew it was RSA, breaking into a house is still easier [xkcd.com] than running a quantum computer. The FBI is pretty expert in this type of crime.

This operation was probably cheaper and took less time than getting access to the box at Fort Meade.

## Re: (Score:2)

Yeah, that's true. Note: factoring isn't NP-complete! So far there's no reason to believe it's not an "easy" problem, except that we haven't figured out how to do it.

Much like people work under the assumption that factoring is hard, you are working under the assumption that factoring is not NP-Complete. Nobody has proven this either...

That's true, but it's a pretty safe assumption. Integer factorization has been proven to be in both NP and CoNP, so if it's NP-complete that would mean that NP=CoNP. This, in turn, would imply that NP=PH [wikipedia.org]. This would be, suffice it to say, very surprising.

## For all my encryption cracking needs... (Score:5, Insightful)

I rely on magic pixie dust found on top of the space elevator. It's easier to get than a useful quantum computer and will be for quite some time.

## Re: (Score:3)

I rely on magic pixie dust found on top of the space elevator. It's easier to get than a useful quantum computer and will be for quite some time.

And if you do get cracked, you just snort some of the dust and then you don't care anyway.

## Re: (Score:2)

Right. And 640K should be enough for anyone too, right?

Qubits have already been demonstrated with great coherence times and we're now making great advances in fabrication so they can be scaled up to thousands of qubits and well beyond. There's no reason to believe that we won't have quantum machines with computational power meeting (if not exceeding, by a large margin) today's classical machines within a generation. Then again, if you refuse to seriously consider any technological innovation that takes more

## CWMike (Score:5, Informative)

Anyone prepared to take a bet that the CW of CWMike stands for ComputerWorld, and this is a blatant attempt to drive traffic towards an article he either wrote or published?

## Re:CWMike (Score:5, Informative)

Pretty obvious really -- CWMike along with Julie188 have been plaguing Slashdot with this InfoWorld/ComputerWorld tripe for years. The articles are almost always either sensationalism (magic future computing may crack your password, clock is ticking!) or trolling flamebait (is [insert favorite mobile OS] dangerous?). It's bullshit blogspam and Slashdot can do better. I just wish they cared a bit more about weeding out this kind of stuff.

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## Useless article (Score:2)

Basically, quantum computers could do magic on encryption, probably, in the future, possibly in 20 years?

Also possible: flying cars, cold fusion and immortality.

## Cracking isn't the problem (Score:2)

It is checking the guessed key is right that is the problem.

Say I take my credit card 4111 1111 1111 1111 and encrypt it with a numeric Caesar cypher, it turns out the encryption is bad but close 90% of the keys you brute force will give you what appears to be a valid answer (assuming mod 10 and 3/4/5 on the 1st digit checks only). If you take the same number with spaces and a EOL and used export grade DES you can try 2^40 keys but only a fraction will result what looks like a credit card number. If you u

## Re:Cracking isn't the problem (Score:5, Informative)

Thing is, much of the time you can be pretty sure that a particular string of plaintext will appear at least somewhere in the decrypted result.

In the case of your credit card number, for example, there's a few things we can do to eliminate most of the apparently valid numbers:

## Re: (Score:3)

http://en.wikipedia.org/wiki/Bank_card_number [wikipedia.org]

http://en.wikipedia.org/wiki/Luhn_algorithm [wikipedia.org]

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## What exactly is being broken by quantum computers? (Score:5, Interesting)

People generally mention that quantum computing will spell the doom for current crypto, but from what I read on different sites, it seems that it's not exactly that. So I would really appreciate if somebody could clarify it. For instance, on Wikipedia there is this:

So, the problem is only for public key crypto, and for AES we just switch to 512 bit keys and no problem? Also if quantum computers don't do all that great against AES, wouldn't be it just a problem of finding somethinig else they have trouble with that could be used for public key crypto?

## Not exactly (Score:4, Interesting)

Quantum computers can factor the product of two prime numbers in polynomial time, so RSA would be broken. A modification of that algorithm allows certain cases of the discrete logarithm problem to be solved efficiently as well, so DH and ElGamal would be broken also. Luckily, quantum computers are not yet known to be able to solve NP complete problems in polynomial time, so cryptosystems based on NP complete problems (Polly Cracker systems, for example) would still be secure assuming that P != NP. There are also hard lattice problems which quantum computers are not known to be more efficient at solving, which can be used to construct cryptosystems, and there was an early public key cryptosystem based on a group theoretic problem which is known to be secure against quantum computing.

So basically, quantum computing is not really a problem at all, at least not in a theoretical sense. It throws a bit of a wrench into some standard hardness assumptions, but nothing too bad.

## Re: (Score:2)

"For one, AES is designed to have fixed key sizes, so "just switching to 512 bits" is not as trivial as you may think."Err, no. AES was based on a simplification of Rijndael, which was designed for arbitrary key lengths. It should be fairly easy to adapt the AES algorithm to longer keys.

Maybe not trivial, but likely not that hard.

## Re: (Score:2)

workfor arbitrary key sizes, but there is no guarantee or reason to believe that a 512 bit Rijndael would actually be more secure than 256 bit Rijndael (or that it would not be less secure, though this is not likely). Rijndael is not a provably secure cipher, so claimin## Re: (Score:3)

## Re: (Score:2)

To make matters worse. A n bit quantum computer cannot simulate a (n+1) bit quantum compu

## Re:What exactly is being broken by quantum compute (Score:4, Informative)

So, the problem is only for public key crypto, and for AES we just switch to 512 bit keys and no problem?Not necessarily. At present we know of a small number of quantum algorithms for problems such as factorization and database search. There are some brilliant theorists working on these things, but the total amount of (wo)manpower being applied to these problems is constrained by the fact that we don't really have any quantum computers to use this stuff with. A consequence of this is that there are vastly more problems for which we

don'thave a quantum algorithm than those for which we do.This has led to a lot of interest in 'post-quantum cryptography' and flood of research papers proposing new public-key cryptosystems based on mathematical problems we don't know how to solve with quantum computers. Another poster mentioned the McEliece cryptosystem, which is based on problems in coding theory. That's a little bit old-school. The new hotness is lattice problems [wikipedia.org] --- go to any top academic crypto conference and you'll see a bunch of papers using these. If you're really interested in this stuff, here's a pretty good intro to a book on the subject of post-quantum crypto [pqcrypto.org].

However, all this talk is good for researchers in non-standard areas, but it shouldn't lead anyone to be overconfident that these problems will

stayresistant to quantum solutions. You can more or less bank on there being some future 'golden age of quantum computing theory' which should take off right about the same time useful quantum computers become available. Predictably, the problems that receive the most attention will be the ones most widely used at the time --- including the ones underlying the most widely used cryptosystems.The one other thing I should mention is that there's a big difference between finding quantum algorithms for fundamental problems such as database search (Grover's algorithm) or number theoretic problems (Shor's algorithm) and finding quantum algorithms for extremely complex specialized systems like AES. Finding an algorithm that solves a major number theory problem is a big contribution --- if you break a particular cryptosystem, people will just shift away from it eventually and your work will become a footnote. Simultaneously, developing an algorithm that attacks AES is enormously harder using the relatively primitive techniques we currently have. So while right now our best approach to breaking symmetric algorithms is to use generic tools like Grover's algorithm, that's not aways guaranteed to be the case.

Of course, crypto's important to us and the chance for a quantum-resistant cryptosystem is better than none at all, so this is still useful work. If you care about your crypto you need to this stuff it all with a little grain of salt, and hope that QCs are far in the future.

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## The silver lining (Score:4, Insightful)

But within the foreseeable future, cracking those same codes could become trivial, thanks to quantum computing

At least the number of burglaries will go down

## Cryptography, eh? (Score:4, Insightful)

Quantum computing could break known

asymmetric cyphers, not symmetric. I'm not aware of any quantum solution to breaking any modern popular symmetric algorithms.Also worth mentioning is that there's really no way the FBI could have known exactly what they'd find. They broke into a home and recovered lots of information, one piece of which proved useful to decrypting messages. If they hadn't found that, who knows what they would have done? Point is don't lower your guard yet - this isn't proof that encryption is rock solid so much as evidence in that direction.

In the end, let's assume unbreakable encryption is readily available. The weakness is in the human factor, since (ultimately) humans have to, at some point, interact with that encryption for it to contain useful information. Looking at the direction England and other countries are going, a government's solution isn't to invest in supercomputers to attack the cryptography; it's to create a set of laws criminalizing a failure to decrypt. Such a failure would be penalized by as much (or more, given the absurd magnitude of criminal damages associated with most modern electronic-targeting laws) as the charges against you for which the cyphertext is relevant. Your information could be protected until the end of the universe while your corpse rots away for some form of electronic obstruction of justice.

There is a pervasive attitude of "

If you have done nothing wrong, you have nothing to hide" that seems to be driving a lot of the thrust behind modern laws and solutions. A jury could be (and has been) biased against you just for possession of encrypted material. Why would a legitimate person need to encrypt their documents? Why wouldn't they decrypt them for authorities? "Because they're mine, not yours, and not the government's" isn't something a lot of people sympathize with. I suppose the point I'm trying to make is, while progress on the cryptographic front to stay ahead of authorities (and "bad guys", and the intersection of the two) is critical, it's also critical to enforce a right to innocently encrypt data in the first place.But sorry to be predominantly negative - overall, a great article that exposes the world of cryptography (and its importance) in terms a layman could understand.

## Re: (Score:2)

I'm not aware of any quantum solution to breaking any modern popular symmetric algorithms.http://www.springerlink.com/content/u4877618u916720g/ [springerlink.com]

3DES is still quite popular, you know.

## Re: (Score:2)

## Entering one of the spies' homes (Score:2)

They can look for extra CC's, books, address books, rolodex, business card, photos get noted, hobbies, signs of other crimes..

When they walk out they may have a pw and a whole new area area of inquiries.

But think back to the foreseeable past, most of what was sold on the commercial/telco and NATO market has been weakened in someway. Tempest leaks or design flaws allowed dreamy Enigma like plaintext decrypting or plaintext entry to be collected.

http://cry [cryptome.org]

## The clock is not tickling me... (Score:2)

Second, there are more and more people who suspect that quantum computers may be a pipe dream : http://arstechnica.com/science/news/2010/06/magic-quantum-wand-does-not-vanish-hard-maths.ars [arstechnica.com]

It has been a good way to make people invest in fundamental research though

## It's a wetware issue (Score:2)

It's not your complex 27 character password that's the problem, it's the 8 bit, John the Ripper-rapeable password of the person you email that's the problem.

## Re: (Score:2)

No, the problem is

The 27 letter password should have been memorizable

If IT Morons insist in a too complex password that changes all the time

then noting it down is the only way to keep access to the system.

Remember that if the password changes FBI will just break in again and see the note

Relative complex passwords that are easly memorizable are better.

## *slaps head* (Score:2)

What in the HELL is the point of a 27-character password if you're going to

write it down?People can go so egregiously far off the deep end to protect their security and then make the most basic of mistakes. A password of half that length with a decent encryption process would be nearly inconceivable to break in any practical length of time.

## Re: (Score:2)

What in the HELL is the point of a 27-character password if you're going to write it down?People that haven't been taught to remember a phrase rather than a password.

On complex password I have for example, is 30 characters long -- 3 orders of magnitude stronger than a 128bit phrase, even if you knew it was entirely lowercase.

Then you get stupid password systems which state your password must be "at least 6 letters, including 1 upper case and 1 number", about 38 bits. Or even worse "between 6 and 8 character

## Re:*slaps head* (Score:4, Insightful)

Then you get stupid password systems which state your password must be "at least 6 letters, including 1 upper case and 1 number", about 38 bits. Or even worse "between 6 and 8 characters".

Those systems are generally not trying to protect against people with direct access to the encrypted data files. Instead, they are *login* passwords for systems where attackers do not have direct access to the protected data.

In principle, each of those systems should detect repeat login failures and delay or deny further attempts. In that case, the attacker doesn't get to try countless thousands of guesses. Security holes are very common in those types of systems, but it's not necessarily just because the password is 8 characters long.

## Thank goodnes! (Score:3)

Must contain upper and lower case. Must contain at least one number. Must be EIGHT characters long.

This means my 'Passw0rd' is OK.

## Re: (Score:2)

The tough new standard? Must contain upper and lower case. Must contain at least one number. Must be EIGHT characters long.

The next logical step would be to mandate that everybody's password must be "Gv7nLXyP".

## One more thing (Score:2)

## One-time pad encryption (Score:2)

One-time pad encryption doesn't care how much compute power, quantum or otherwise, you throw at it. If you don't have the key, you don't have the message. Period.

I've sometimes thought it would be fun to hook something really random (like a geiger counter) up to my computer, generate a DVD full of

reallyrandom encryption keys, send a copy to my Mom, and we could send email that even the NSA couldn't read....laura

## Re: (Score:2)

The other nice thing about OTP is that for a given encrypted message, you can create an OTP that produces any message you want.

So, for example, if the message gets intercepted and the NSA demands you produce the OTP key, you can provide one that decrypts the message into a recipe for cranberry muffins.

## Re: (Score:2)

And what if the NSA intercepts the one-time pad DVD before it gets to your Mom?

## All Encryption Is Equally Easy to Break (Score:2)

## Re:Quantum Encryption (Score:5, Funny)

only if you don't actually want to crack it, then quantum encryption will unlock itself, however if you want to crack it you can't.

## And the news here is what? (Score:3)

## Re:And the news here is what? (Score:4, Informative)

However not all encryption algorithms can be cracked using quantum computers. The quantum computer cracking of encryption relies on the factorization algorithm and prime numbers but if an encryption is based on another technology the quantum computers aren't a help.

So the Navajo code talkers are still safe.

## Re: (Score:3)

256 bit hash, triple blowfish, AES outer envelope, Micro-SDHC card in a hollow coin, in a coin tray on your dresser.

## Re: (Score:2)

I was under the impression that some of the crypto algorithms were safe from quantum computing.

## Re:Quantum Encryption (Score:5, Informative)

Quantum computing is probabilistic, it has a chance to converge on the right answer, and it gets there in the fairly specific case of using a quantum version of a fourier transform to factor large primes. If you base your crypto method on something not vulnerable to to a quantum fourier transform, or if, with your decryption method you absolutely must get the right answer, you can end up back at brute force.

Quantum cryptography is really not related to quantum computing all that much. They both rely on entanglement, but trying to extract some quantum state of two entangled things (nuclear or electron states most likely) isn't really a computational problem that computing, quantum or otherwise exists to solve. There are lots of practical challenges to quantum cryptography, the short version of which is that a single thing in a specific quantum state is hard to pin down, but lots of stuff (polarized light, atoms in excited states etc.) all happen with a distribution of states. If you were to communicate inside a device this limitation isn't really a problem, but if you need to send data from New York to LA it's very hard to send a single photon or atom (at least for the moment), and if you're sending a million photons, in some collection of quantum states it's somewhat harder to guarantee security. I'm being a bit handwavy here, but a few years ago I did a simple demo quantum crypto project with polarized light, for a couple of hundred dollars in hardware borrowed from an optics lab for an afternoon it worked pretty well. Over the length of a table. Scaling up to fibre optics that move any meaningful distance isn't impossible, but if done wrong you end up rapidly defeating your own crypto system.

For those who don't know, a quantum computer can factor products of primes in polynomial time, with a certain probability of success, but right now because you can't build quantum computer which more than a few qubits you are limited to trivial problems. If you could build a multi-million qubit system you could, with a certain probability of success, factor large products primes such as those used in cryptography in polynomial time.

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## Re: (Score:3)

probably true that a few thousand would suffice for current cryto systems. But you're then into a trivial cat and mouse game. If it's easy to factor a 4 bit product of primes with a quantum computer, use 16 or 32. If it's easy to build a quantum computer to factor 256 bit RSA with a few thousand gates, well use 1024. If building a crypto system scales more easily than the quantum computer does, well, you're still ahead.

The problem of qubits though is more subtle than just the record being a 7 or 8 qubit

## Re: (Score:3)

I'm not well-versed in Shor's algorithm, but since the number of operations required scales polynomially, I suspect that the time that a given machine takes to factor a number scales polynomially with the number of bits. A 1064 bit encryption would just take 4 times longer. That doesn't make moving to longer keys a viable solution.

The trouble right now doesn't lie in whether or not Intel's resources are being thrown at it; Intel can't fab ion traps. Fundamentally new ideas regarding producing and interactin

## Re: (Score:3, Funny)

I have an algorithm that lets me factor any number with runtime complexity O(1) with a probability 1/(2^log2(n)) and can run on any system with support for /dev/random. No need for expensive quantum hardware. Preliminary tests have been able to break 4-bit RSA quite reliably. Encryption as we know it is doomed.

Where should I go to collect my grant money?

PS: You can leave the Nobel Prize next to my garden gnome. Thanks.

## Re: (Score:2)

I have an algorithm that lets me factor any number with runtime complexity O(1) with a probability 1/(2^log2(n)) and can run on any system with support for /dev/random. No need for expensive quantum hardware. Preliminary tests have been able to break 4-bit RSA quite reliably. Encryption as we know it is doomed.

Where should I go to collect my grant money?

PS: You can leave the Nobel Prize next to my garden gnome. Thanks.

The Prize will be encrypted as a second gnome.

If you reach for the wrong one, then the prize vanishes.

## Re: (Score:2)

it gets there in the fairly specific case of using a quantum version of a fourier transform to factor large primes.

Bill Gates, is that you? [wikipedia.org]

I think I know of a better algorithm to factor large primes ;)

## Re: (Score:2)

So you check the answer and, if it's wrong, try again until it isn't.

The probabilistic correctness isn't an issue except in toy problems, especially as you could in the limit just repeat the operation until the chance of it going wrong is less than the chance of the operator going wrong.

## no need for multi-million qubits (Score:5, Interesting)

A couple of thousands do (about 5 times the lenght of the number you want to factor). But what you really need is the ability to perform multi-billion

gate-operations(while the QFT itself is quadratic, Shor also uses modular exponentiation which makes it a cubic O(n^3) algorithm) within the decoherence time (usually measured in milliseconds or seconds)andwith a technical accuracy to the tune of 99.9999999% - a quantum computer is, after all, an analogous device: qubits don't "lock in"; a NOT-gate e.g. thus has to be an exact 180 deg; rotation and neither 179.999 nor 180.001 deg (does not matter for a couple of gates in toy problems but those imperfections add up).Quantum error correction can somewhat mitigate the former problem (at the cost of about one order of magnitude overhead in both space and time) but not the later. So if it's feasible at all (which is by no means certain as there might be hidden constraints on scalability), we probably won't live to see it.

ignatius

## Re: (Score:2)

If you base your crypto method on something not vulnerable to to a quantum fourier transform, or if, with your decryption method you absolutely must get the right answer, you can end up back at brute force.

First half: right. Second half: misleading.

If you work the same factorization problem multiple times with a quantum computer, the likelihood that all of those factorizations are wrong decays exponentially with the number of times you work the problem. It is trivial to check which factorization is right using a classical computer.

So yes, quantum cracking will say "Could Not Crack" some percent of the time, but that percentage can easily be made as small as you want just by resubmitting the problem to the q

## Re: (Score:3)

Proper quantum computation (like Shor's Algorithm) isn't probabilistic at all.

Also, you don't need millions of qbits to factor primes. You need on the order of 10x the number of bits in the prime.

## Re:Quantum Encryption (Score:4, Informative)

Hash functions and symmetric ciphers are somewhat safe against quantum computers. A quantum computer can give a significant speedup, but only to the point of reducing the strength to half the number of bits it would otherwise have. So, just design the algorithms to work with twice as many bits as needed to break them on a classical computer, and they will most likely be secured against a quantum computer as well.

However public key encryption schemes (especially those built on factorization like RSA) can be broken much faster on a quantum computer. For those just increasing the key length isn't sufficient to give you the edge you need to protect against quantum computers. Research is happening in the field of developing public key schemes that are secure against quantum computers, but I don't know what the current state of that is.

There is a major difference. You don't need a quantum computer to do quantum cryptography. You need a device that can send single qubits, and a device that can receive and measure them. But these devices don't need to work on more than one bit at a time, so they are not really quantum computers. The algorithms do involve a lot of computation, but that computation happens on a classical computer which is doing computation on the data before and after it has been in the state of qubits.

There is a method to increase the range at which quantum encryption can work, which involve quantum computers. You cannot use a classical repeater with qubits because the repeater would collapse the quantum state in pretty much the same way an eavesdropper would. Instead you would use devices that takes advantage of entanglement of qubits. Each such device will require a 2-bit quantum computer in order to work. But a 2-bit quantum computer is no use for breaking any sort of encryption. The encryptions that you could break using a 2-bit quantum computer are much easier to break using a classical computer and a lookup table of all the possible keys.

## Re: (Score:3, Funny)

Yes it will. Just because the encryption is "quantum" does not mean it's not trivially breakable with rubber hose cryptanalysis.

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Truecrypt uses the first 1024 bytes of the key file only [truecrypt.org], and though not likely at this time, collision attacks [wikipedia.org] could be a potential vector of attack with, and when, quantum processing becomes available.

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Will quantum encryption be similarly trivial to crack?

"quantum encryption" is not an encryption per se, but a method of sending sensitive information

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Can't actually store quantum-encrypted informati

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First, the way current Quantum Encryption works is just for a key exchange. In reality, a Quantum Key Exchange is a way to collaborate and cooperatively generate a key, not a way to transmit arbitrary bits. It relies on the fact that if Alice and Bob are exchanging a key, half of the bits Bob gets are going to be wrong, and he won't know which ones until they talk about it afterwards. An intermediary can't intercept the key and still make sure it gets to Bob, be

## Re:petrabit encryption (Score:2)

Rocks are indeed mysterious. However, you probably meant petabit encryption.

## Re:Quantum Encryption (Score:4, Insightful)

If you want real security, go with a one-time pad and read up on the mistakes the Kriegsmarine made that let their nifty device get cracked.

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Side effects include turning into a spambot touting the virtues of moldy tea.

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Make sure you read the hover text. :)

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