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Chinese Prof Cracks SHA-1 Data Encryption Scheme
Hades1010 writes to mention an article in the Epoch Times (a Chinese newspaper) about a brilliant Chinese professor who has cracked her fifth encryption scheme in ten years. This one's a doozy, too: she and her team have taken out the SHA-1 scheme, which includes the (highly thought of) MD5 algorithm. As a result, the U.S. government and major corporations will cease using the scheme within the next few years. From the article: " These two main algorithms are currently the crucial technology that electronic signatures and many other password securities use throughout the international community. They are widely used in banking, securities, and e-commerce. SHA-1 has been recognized as the cornerstone for modern Internet security. According to the article, in the early stages of Wang's research, there were other data encryption researchers who tried to crack it. However, none of them succeeded. This is why in 15 years Hash research had become the domain of hopeless research in many scientists' minds. "
I'm a big fan of teams like this in unraveling the security defects out there -- giving others more reason to make more secure schemes. I'd love to know how one can finance these groups (legally?). What does her group specifically gain from all this labor? Who pays for them?
It looks like she did this almost 2 years ago. So why is this being announced now?
Aside from confusing hashing with real encryption, and saying that MD5 is part of SHA-1, isn't this article just repeating what was covered in these two slashdot stories?
Ewige Blumenkraft.
The article doesn't make sense. There are no technical details and SHA-1 is a cryptographic digest algorithm, not an encryption algorithm. AES is what everyone uses for encryption now -- message digests are used for signatures. Important, yes, but encryption hasn't been rendered useless.
They also use the word "online" too many times for me to take them seriously. The implication is that because the professor broke SHA 1 that my online bank account is going to be drained. Not likely.
My other car is first.
This article is completely devoid of any real content. It just says she "cracked it" over and over, not explaining whether a crack is a collision, preimage, or other attack. It also seems technically inaccurate, saying that SHA-1 'includes' MD5? I know that no one RTFA, but c'mon, at least cover for a crappy article by having a good summary: this story has neither.
The original article is full of misstatements like this doozy:
this SHA-1 encryption includes the world's gold standard Message-Digest algorithm 5 (MD5). Before Professor Wang cracked it, the MD5 could only be deciphered by today's fastest supercomputer running codes for more than a million years.
SHA-1 is NOT encryption, and it certainly doesn't "include" MD5. They are 2 completely different hashing algorithms. Hash algorithms are not "deciphered". Neither of them has been "cracked". They have been found, in theory, to not be as collision-proof as previously thought, but noone has yet found a way to take one block of data and modify it such that it would have an identical hash signature as the original. Both are merely found to be not quite as collision-proof (the most important thing for any hashing algorithm) as previously thought. This is old news.
The original article blows and contains no useful information whatsoever, it was written by someone who hasn't the faintest hint of knowledge about cryptography or mathematics in general.
"Well said. I'm pretty sure that this is just the English translation of a Chinese state-run newspaper. (The "read original Chinese" link at the bottom gives this away.)"
Errr, you are aware that the Epoch Times is a virulently anti-Communist newspaper don't you? They're famous for doing some sort of 10-part history of Chinese Communism (which read like a lurid and hysterical diatribe. I picked up a copy once; I don't know much about the history of China but they had a summary of the Paris Commune of 1871 which was an utterly atrocious travesty of history). If anything, the Epoch times is far more likely to distort the facts in a manner that defames the Chinese government, hard as that may be to believe.
Not everything written in the Chinese language is censored by the Chinese government
"Do the editors read ANYTHING before posting!?"
I find the irony of THIS statement quite remarkable, given the above.
Makes me wonder just how much trouble the US or international financial community would be in if an adversarial organization cracked a major security encryption and didn't politely announce it, but instead kept their achievement secret. And then either cracked mountains of banking/military data at a leisurely pace, selling it piecemeal to finance rogue networks OR timed a widespread release of the crack algorithm for a catastrophic hit upon (inter)national security. What steps are being taken to combat this from eventually occurring?
There are two kinds of people: 1) those who start arrays with one and 1) those who start them with zero.
Gung'f jul V arire hfr nal bs gubfr arjsnatyrq rapelcgvba fpurzrf, guvf bar jbexf, naq fur jvyy arire jevgr n negvpyr ba oernxvat vg.
The Epoch times is a strange newspaper (http://en.wikipedia.org/wiki/The_Epoch_Times) - it seems to be an anti-establishment periodical with lots of fluff stories about people living in China and articles on the Falun gong movement (http://en.wikipedia.org/wiki/Falun_Gong)..
Far from being a Chinese newspaper it's actually published out of New York, and you might see (Chinese) people handing out copies on the street in your country (I see them in NZ from time to time).
So yeah, it wouldn't surprise me if the article was vague... I'd take it all with a grain of salt.
But they are certainly weak against attacks using rainbowtables. Both algorithms should be tossed into the bit bucket for something a little more secure. New services including Hashbreaker, Schmoo, freerainbowtables etc show how easy it is to brute force using rainbowtables. RE: http://www.hashbreaker.com/ and distributed rainbowtable generation http://hashbreaker.com:8700/ http://wired.s6n.com/files/jathias/ http://www.freerainbowtables.com/index-rainbowtabl es-distributed.html/
http://www.darknet.org.uk/2006/02/password-crackin g-with-rainbowcrack-and-rainbow-tables/
-Spudster
Any hash algorithm can be used as a stream cipher: hash the key and take successive values to make a pseudorandom stream, and then XOR it against the plaintext. This is the idea behind Daniel J. Bernstein's Snuffle ciphers.
From the original article cited by the epoch times article (at the moment /.ed)
Busted! A crisis in cryptography
"LAST year, I walked away saying thank God she didn't get a break in SHA-1," says William Burr. "Well, now she has." Burr, a cryptographer at the National Institute of Standards and Technology in Gaithersburg, Maryland, is talking about Xiaoyun Wang, a Chinese cryptographer with a formidable knack for breaking things. Last year Wang, now at Tsinghua University in Beijing, stunned the cryptographic community by breaking a widely used computer security formula called MD5. This year, to Burr's dismay, she went further. Much further."
cute...
In other words, this attack is 2^17, or 131,072 times faster than brute forcing the hash, and from what I've read, this is considered pretty impressive stuff. That said, crypto researchers have known for a while that SHA-1 is on its last legs. From Schneider's blog in February, 2005: Jon Callas, PGP's CTO, put it best: "It's time to walk, but not run, to the fire exits. You don't see smoke, but the fire alarms have gone off." That's basically what I said last August. So there's nothing much to see here, except a sensationalist newspaper article. This has almost certainly been reported before on Slashdot two years ago, so this story probably counts as a dupe.
All your bank, are belong to us.
We are all just people.
Without bothering to read the article, I will point out that as far as your bank is concerned, digest algorithms protect SSL negotiation in general and the key exchange in particular. A worst-case break in SHA-1 and MD5 can negate the protections provided by RSA and AES.
A short note about the attack has been available for a couple of years as well. The note shows collisions for two different reduced versions of SHA-1.
Though it's not absolutely certain, my guess is that the reality behind the new announcement is that they've actually found a collision for the full version of SHA-1, and possibly for MD-5 as well. OTOH, maybe the mention of MD-5 is just a journalist's hashed (no pun intended) version of the fact that SHA-1 is based closely enough on MD-5 that an algorithm that's successful against SHA-1 will probably be effective with respect to MD-5 as well.
The universe is a figment of its own imagination.
The probability is very small in a random universe, not any one you pick. And it still only implies a finite number of universes. And the correct spelling is "astronomically", which however means extremely large. You probably meant "infinitesimally"
That is 1 for school masterism, 0 for responding without thinking.
Here's what you really need to look out for: what's the NSA's reaction?
In the past, it was widely understood that the NSA was well ahead of the private sector in terms of both encryption and decryption. During the 70s and 80s, the private sector basically closed the "encryption gap" and produced some ciphers that (at least most people suspect) are as secure as those used by the NSA.
What's still an open question, is how far ahead the NSA is of the private/corporate sector in terms of breaking other people's ciphers.
Depending on the NSA's reaction, it might be possible to know whether or not this break was anticipated. If they're using SHA-1 internally, one can assume they didn't know about this discovery already, and they've fallen behind of the position many folks assumed they had. If they just shrug and smile, then they may have already known about this (and possibly been using it) for some time now.
"Ladies and gentlemen, my killbot features Lotus Notes and a machine gun. It is the finest available."
This appears to be the professors website:
h tm
l isions%20in%20the%20Full%20SHA-1.pdf
e arch%20Attacks%20on%20SHA1.pdf
http://www.infosec.sdu.edu.cn/people/wangxiaoyun.
The details on the hash collision can be found in the following papers:
Xiaoyun Wang, Yiqun Yin, Hongbo Yu, Finding Collisions in the Full SHA-1,Crypto'05
http://www.infosec.sdu.edu.cn/paper/Finding%20Col
Xiaoyun Wang, Yiqun Yin, Hongbo Yu, Collision Search Attacks on SHA1,2005
http://www.infosec.sdu.edu.cn/paper/Collision%20S
She has also previously found methods for collisions in X.509, MD4/MD5, HAVAL-128, RIPEMD and SHA-0.
However, the problem is not entirely the algorithms, there will always be collisions on hashing algorithms, if you could represent an infinite amount of data in 160/128/whatever bits then there would be no point in having 161/129/whatever bits, the fact that your hard drive is much larger than that is a testament that collisions in any type of algorithm where you try to uniquely represent X bits in Y bits (where X > Y) (Yes I realize this is a somewhat oversimplified exaplantion).
The problem is in the paradigm in which these algorithms get used, 'one hash to represent them all' is a broken mentality, use multiple hashing algorithms when it matters, while it is indeed possible that the same data can cause a collision in all of the employed algorithms, its incredibly unlikely and AFAIK no one has created a PoC where two sets of data produce the same checksum in both md4 and sha-0.
Incredibly old news. EE Times reported on it at the time, correctly referring to SHA-1 as a hashing algorithm, nothing more... by itself, anyway.
Just so you know, SHA-1 is a hash, not an encryption algorithm. You can't really encrypt anything with it because you wouldn't be-able to get the plaintext back. Which is kinda the (one way) point of hashes....
I disagree with your assessment of MD5 and the majority of uses of it. There is a property of MD5 which is broken. It is possible to construct two bytestrings that have the same MD5 hash. In fact, it's relatively easy to.
This breaks an important property that most people assume is true about cryptographic hash functions. I think it's actually very hard, in practice, to determine whether or not losing that property renders a particular system more vulnerable to attack. I don't believe that downplaying the associated risk does anybody any favors. I believe MD5 should be treated as "Effort should be made to remove the use of this algorithm from any existing code unless a convincing case can be made that the break doesn't affect it.".
SHA-1 is similarly 'broken'. But, the break in SHA-1 is not currently computationally trivial to exploit. It is just less computationally expensive than it should be to generate two bytestrings with the same SHA-1 hash than it should be given the length of the hash. But once people start discovering weaknesses in algorithms, it's common that someone refines the technique to make the weakness worse. So, I would treat SHA-1 as "No new code should use this, and it should be removed from existing code if the required effort isn't very large.".
The biggest problem is that there isn't a clear algorithm to move to from SHA-1. SHA-256 and SHA-512 are based on the same principles as SHA-1, so there is worry (but no proof) that the break in SHA-1 could be extended to these two hash functions as well. But WHIRLPOOL, the other major contender, has received very little scrutiny.
I've save a bunch of interesting links about hash functions on del.icio.us.
Need a Python, C++, Unix, Linux develop
rehashed story makes collision attacks ^2 as bad ! doh !
It is actually run by the notorious Fa Lun Gong cult. The 'epoch' here refers to the new era the cult is supposed to bring us into, with the leader kind like Jesus. A lot of the stuff on that media, especially the Chinese version, is total crap. Despite its lack of credibility, Epoch Times seems always have quite a lot of money to burn. You can sort of pick up the recent copy FREE at major convenience shops in your local Chinatown, amongst stuff like Jehovah Witness's pamphlets. I even once found copies of both language versions at a community library here in UK.
People who dislike China tend to mention Tiananmen Square a lot, but they always forget the Tank Man is also a Chinese.
Block ciphers and hash algorithms are basically the same thing in two different modes. If you look at the SHA-1 algorithm, you'll notice that the main part of the algorithm is taking a 160-bit input (previous hash) and a 512-bit input (data to hash) and producing a 160-bit result (new hash).
Something about the SHA-1 algorithm is that if you know the 512 bits of data and the 160-bit output, you can find the 160-bit input. Just do all the rounds in reverse. This means that if you rearrange the parameters, you can make a 160-bit block cipher: the 512 bits are the key, and the 160 bits are the block to be encrypted. Knowing the key lets you reverse the whole thing. This is what the SHACAL algorithm is.
You can turn a block cipher into a hash algorithm as well, by using the data to be encrypted as the key.
Block ciphers and hash algorithms are designed with different security goals, however. A block cipher cares most that you can't find the key if given plaintext/ciphertext pairs. A hash algorithm cares most that two keys do not have the same effect, because those two keys are a hash collision by definition. As a real-world example, the "Tiny Encryption Algorithm" has a flaw where each key functions identically to 3 others. On a block cipher, this means that the algorithm is 4 times weaker, because there are 1/4 the keys - not a big deal if the keys are big enough. When using it as a hash algorithm, however, it means that each input has 3 other easily-found inputs that have the same hash! This is what the piracy group Xecutor exploited to break the "version 1.1" Xbox.
"Screw Sun, cross-platform will never work. Let's move on and steal the Java language." - Visual J++ Product Manager
>I think it's actually very hard, in practice, to determine whether or not losing that property renders a particular system more vulnerable to attack.
It is computationally feasible, now, to build collding X.509 certificates.
It is possible, in some common environments and with a little cleverness, to Create two documents which are both human-readable and meaningful and which have the same MD5 hash.
Those are attacks which a collision-resistant hash function is supposed to prevent.
A collision-resistant hash function which has been shown not to be collision-resistant is broken. As of today, there's no published way for someone to start with a file you created and match its MD5 with a document they created. But in the case where an attacker can generate both files (say, the new $MUSTHAVE binary that gets signed by the repository and the separate binary with the same MD5 that contains a Trojan) MD5 has lost its usefulness.
I still think the fact that a hash algorithm is broken can be relatively unimportant. I mean, for your average Linux distribution, if you want to trick someone into using your 'fake' iso, you will have to change the bits you want to change to make certain software vulnerable, or malignant, and then you will have to make sure it is giving the exact same checksum. You are not just looking for some collissions. The collissions have to be useful to you as well.
My question is, how trivial is it to create, say, a binary that features the command "take over user's computer" whilst keeping the same hash as the original.
The question I would ask myself is, what is easier, cracking the website where the program is stored, and replacing the hashes with the hashes of my binary, or trying to come up with a working binary that has my misfeatures in it. I still think that if you can make things difficult enough, then you have achieved the objective. Isn't this the idea behind crypto/hashes anyway. They are not 100% foolproof, but the required level is so hard as to not be worth it.
Coral cache here. Sorry, the original link was from the chinese server.
TFA refers to its own source as the New Scientist. A quick search there reveals the article in question is dated February 2005. So I guess this should probably come under "oldnews", but in any case the NSA had had plenty of time to play with it.
What concerns me is that in the last two years I've heard no news about a replacement for SHA-1. Maybe every's hoping that if they ignore the problem, it'll go away.
"According to a Beijing digest, this SHA-1 encryption includes the world's gold standard Message-Digest algorithm 5 (MD5)."
Where do I start? SHA-1 stands for 'Secure Hash Algorithm 1' and is not an encryption scheme. Neither does it include MD5 which is a completely different hash (or message digest) algorithm.
See Schneier - http://www.schneier.com/blog/archives/2005/02/sha1 _broken.html
and http://www.schneier.com/blog/archives/2005/02/cryp tanalysis_o.html for actual coverage of the break. "They can find collisions in SHA-1 in 2**69 calculations, about 2,000 times faster than brute force. Right now, that is just on the far edge of feasibility with current technology. Two comparable massive computations illustrate that point." That's down from 2**80, so it's a concern, but not exactly the end of the world.
New apps being written should probably be using SHA-256 (256 bits) rather than with SHA1 (160 bits only).
"It doesn't cost enough, and it makes too much sense."
Now you're confusing me. I think you're trying hard to say SOMETHING as a retort, because I pointed out how you made an ass of yourself in your previous post, but what you actually mean by this latest post I can't decipher.
Wang Xiaoyun lives and researches in Beijing. Whether she's a communist or an anti-communist or not, I don't know, but the fact that both the Chinese government, and it's US-based enemies have published relatively uncritical articles on this research does tend to give it a bit of credibility; you desperately want to dismiss this as some sinister Chinese propaganda, but when the propagandists on both sides of the fence say the same thing, then it gets a bit confusing as to what sort of propaganda we're talking about here. Maybe there's no propaganda angle here at all; maybe this is (shock) news!
Now the article is pretty badly written, but the news in it seems perfectly plausible; the same researcher was after all, one of the authors of the peer-reviewed attack in a European journal that discovered ways of constructing collisions in MD5, and has appeared at a crypto conference with collisions on the MD4 scheme. Why don't you think she's able to crack SHA-1? Because she's Chinese? Because she's in a country with communists in it? Because some anti-communists wrote a newspaper article about her? Because SHA-1 is sooper-seekrit NSA stuff that is uncrackable?
Give up now, please. You're flailing.
Oh.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
Sun has been investing in Elliptic Curve Cryptography for many years. Now that SHA1 has been broken, ECC appears to be urgently needed as a strong encryption replacement for common internet usage. According to the Sun Labs page, ECC is also a high-performance technology.
Zen tips: Pay attention. Don't take it personally. Believe nothing.
SHA-2 is a new family of hash algorithms. But that's kind of like saying that Twofish is a new cipher algorithm that isn't Blowfish. Realistically, if someone finds a major flaw in Blowfish that wasn't anticipated in the design of Twofish, it's quite possible that Twofish has the same flaw because they're built along the same lines, despite being different algorithms.
The SHA-2 family is designed by the same people who designed the SHA-1 algorithm, and they were designed before the flaws in SHA-1 were discovered. And from what I understand, the internal structure of SHA-1 and algorithms in the SHA-2 family are very similar.
Need a Python, C++, Unix, Linux develop
It is relatively easy with MD5. It would probably require less than a week of time on a modern computer, possibly only hours.
If you spent 10 million on an SHA-1 cracking box, it's estimated that it would take about 127 days to find two colliding files.
Here is a PDF that's my source for this information.
An additional problem is that you can embed interesting things in .pdf, .ps or even HTML documents. You could embed both the evil code, and the good code. Then use a colliding block someone found a long time ago to choose between the evil code and the good code. So, once even one collision is found, it's possible to leverage that one collision into all kinds of existing documents because of the block nature of the two algorithms.
I expect that .pdf and .ps documents rarely see code review looking for evil code. So it's quite likely something like this would go compeltely undetected until the evil version was released into the wild causing a ton of confusion and lost time before someone figured out what was wrong.
Need a Python, C++, Unix, Linux develop
This exact proposal shows up, like clockwork, literally dozens and dozens of times for each slashdot story about hash functions. Since the number of people who know why this proposal fails is miniscule compared to the number of people who think of the idea, it is literally impossible to respond to all the people who keep suggesting this idea. I mean, even if all of us spent literally every minute of every day responding to people who suggest this idea, we would still not have time to reply to every single post.
Here is an old post on slashdot explaining exactly why this idea doesn't work. The post has some details wrong ... for example, the correct security strength of the combined md5+sha1 hash is in reality 2^80 + 160*2^64, which is much weaker than even the already weakened security level cited in the post. However, the general idea is correct, and if you google for the title of the paper cited in that post, you can find much more information.
I hope that this reply helps to educate at least one poster, but judging by the regularity with which this idea keeps reoccurring, it's a little bit like rearranging chairs on the Titanic.
What moron approved this poorly-written and inaccurate story? Oh wait this is Slashdot.....
Miles, meet Zonk.
BTW, I like how you tactfully left out the fact that it's a dupe.
No. I'm not saying that at all.
I'm saying that people are good or bad, people's actions are good or bad, and it hasn't got a single thing to do with cars, bullets, or highways. That's just evasive nonsense, mumbo jumbo from addled thinkers (or those seeking to escape responsibility.) We're human. We can choose. Choose well, and bear responsibility for good; choose poorly, and bear responsibility for bad. Technology isn't the culprit here. It's you. It's me. It's people.
People make choices. They're responsible for those choices. Highways, guns and communications are not. Any philosophical mumbo jumbo that says the more choices are available the more blame the choices carry, is completely and utterly worthless. Likewise, when technology can amplify a choice we make, we carry additional responsibility; the technology carries none at all. This has been true since the first rock was used with intent to kill.
Responsibility is the lost idea in modern civilization. People do anything to avoid it, to slough it off onto someone else. Well, I'm here to tell you straight out that the existence of a gun makes you no less culpable when you kill someone because it is physically easier to do, and no more respectable when you refrain in the face of whatever tempts you. It is no more or less about you and me than it was a thousand years ago. Science and technology are neutral. We have the power to turn them in either direction. We always have. There's no one here but us, and objects don't make choices. As the power is ours, so is the responsibility. 100%.
Also: If you let media change your mind, that's your responsibility. Media can only be "active" through your actions. In other words, you can always choose. Some choices are more difficult than others, certainly, but who ever promised you an easy ride? If anyone did, they were lying and you were a fool to believe them. Just about every choice you make carries responsibility with it. There's no way out. You can't blame the Internet, highways or weapons for your problems. Your problems come from human sources, at least those that aren't sourced by the ongoing processes of nature. Technology, science... these are the last places to look to place blame.
I've fallen off your lawn, and I can't get up.
Any big group that operates as part of a government, particularly a government as enormous as that of the USA, WITHOUT extensive public oversight, will be hopelessly crippled by earmarking, cronyism, and all other manner of corruption and incompetence. I mean, if the NSA was worth half a shit in a tin can they'd have been able to stop people like McVeigh, Kaczynski, or the doofuses* that thought it would be a good idea to hijack a few planes.
A handful of really bright people working on a project that they truly care about can perform miracles of creativity and insight. If governments really want to get things done, they need to focus more on identifying those people and giving them the support they need -- whether it's a research grant, a loan with which to start a small business, or even just an environment where creativity and hard work are appreciated and respected. A "keep up the good work" now and then can go a long, long way (a woman I talked to who worked in HR suggested that a bit of respect and encouragement could easily avert 90% of the labour issues that her department dealt with BEFORE they became severe enough that HR had to waste time and money on them).
* Doofuses? Just look how well that has worked out for their feelow Muslims... their 70 virgins are probably going to turn out to be 70 desperate truckers with a taste for the dark meat...
Actually, you don't know what you're talking about. Go read "Multicollisions in Iterated Hash Functions. Application to Cascaded Constructions" by Antoine Joux. Unfortunately, it's not generally available online, but Hal Finney wrote a nice explanation of the problem here.
http://outcampaign.org/
Dude, I don't know whether or not she cracked SHA-1, but, as brilliant, 39-year-old, female mathematics professors go, this chick is HOT!!!
Man, what I wouldn't do to make babies with a chick like that...
PC World commented on the issue in 2005
Also Bruce Schneier wrote about it back then.
I guess it takes a while for the US government and Microsoft, et al to take action on the news.
As a direct answer, probably not. I'm not sure that you can prevent choice in any case, or execution of choice (action.) If you try, they'll probably fight you on principle and do it anyway, find a way around the "safeguards", etc. You can react when people make a choice and take action on it; and in many cases, you should. In my view of the optimum world, my rights end where yours begin, and if I step over that line, society has a good case to get rid of me.
Suppressing choice, either by law or by technology, has a way of going afoul of many things, not the least of which are personal liberty and people's safety.
I would even shoot through the hostages to take him out. Any time hostages are used successfully as a line of defense, more hostages will be taken as part of the lesson learned in that event. The robber is outside the pale; he has violated the rights of others by extending his actions where they must not go. He's a valid target now. The hostages are consequences of his choice to take them, and the fact that if they are treated as an impediment to his apprehension or elimination, they will be used to hurt others in the future. In other words, if taking hostages never works, and further, makes it even rougher on the hostage-takers, very few people will take hostages.
No. There may be valid reasons why a person may need to drive drunk to save lives, move their vehicle around on their own land, etc. My take is that driving needs to be an action (like 99% of all actions) where a person's responsibility is to avoid trampling on the rights of others, knowing that society has severe consequences prepared if that line is crossed. Drinking isn't a problem. Driving isn't a problem. The combination isn't a problem. The problem is when other people's rights are trampled upon. So trying to use technology to eliminate drinking and driving is the wrong path. In my opinion.
No, it doesn't. Neither do laws, neither will any technology I am aware of. However, eliminating the criminal will stop them from doing it again, and as far as I am concerned, that is the right choice as soon as we can be sure we have the right "criminal." At this time, I do not support the death penalty because we make so many mistakes in identifying the perpetrator. Life imprisonment unless they can prove they didn't do it, instead. The very day we can know they did it, we kill them.
When thinking of a (presently imaginary) technology used to "stop killing", it is also important to realize that there are many valid scenarios that involve killing. If you enter my home in the dead of night, you've violated my rights and I can kill you. If you attack my family on the street, you've violated their and my rights and I can kill you. If you've taken hostages, you've violated their rights and I can kill you. If you are about to poison a water source, you're going to be violating many people's rights, and I can kill you to stop you. If you attempt to hijack an aircraft, you've violated the othe
I've fallen off your lawn, and I can't get up.