Slashdot Mirror
Slashback: Flashmob, Currency, Verification
Reminder of your scheduled spontaneous appointment. Zero_K writes "As previously posted on Slashdot and the NY Times, the University of San Francisco's, Computer Science department is building a 'flash mob' supercomputer on April 3rd. On their newly updated official web-site (Main Site, ISO's) the team has now posted the ISO image of their custom morphix that will be used to boot all the computers into the cluster, documentation is on the website (under 'downloads') and on the CD (index.html). I personally plan on downloading and testing this ISO tonight. And after the cluster is taken off line, there will be a massive LAN PARTY (Possibly one of the biggest in San Francisco...) On a 10-Gigabit LAN...Oh sweetness ... So if you are in or around the SF Bay Area on April 3rd, be sure to sign up and bring your laptop or desktop to campus and help make history."
Whaddya mean, "no pun intended"? Rudiger writes "After the dust (no pun intended) has settled around the whole Operation Dust Bunny thing, McAfee updates their signature database classifying Dust Bunny as an application. To be more specific: 'This program is detected as a "potentially unwanted application."' They also say 'This is not a virus or trojan.' Should we leave it to the experts this time?"
Would you read Atlas Shrugged on this screen? An anonymous reader writes "The so-called 'electronic paper,' being a high-clarity monochrome display to become a foundation for comfortable and inexpensive 'electronic papers,' has finally shown its face. The new electronic paper, which looks a bit like an iPod, has 10MB memory, keyboard, Memory Stick PRO slot, voice recorder, speaker, and headphones output, and USB2.0 interface."
(We mentioned the device yesterday, but this link provides better images of it.)
Now they're Pragmatic Publishers as well -- much success! AndyHunt writes "As you may have heard, the Pragmatic Programmers have started their own publishing company (see Slashdot reviews here and here). We've just signed our first outside author: Mike Clark, editor of the JUnit FAQ and developer of JUnitPerf and JDepend. He'll be writing the eagerly-anticipated Pragmatic Project Automation book, the third volume in our Jolt Productivity award-winning series."
Exactly how many bits, Ma'am? And in what order, did you say? jlcooke writes "Two months (almost to the day) after getting slashdotted for an innocent post to sci.crypt - the MD5CRK project has launched. The aim is to get the thousands of applications and websites to drop MD5 for SHA-1 or SHA-256 by finding a counter-example of a security requirement in MD5. Press Release is here."
How to take criticism, by example. slashdot_commentator writes "Eric S. Raymond has recently written a wonderful piece explaining to the Linux zealot why it may not be the operating system of choice of all users. (Or what user aspects open source developers need to focus on to further Linux World Domination.) The op-ed specifically focuses on the CUPS printing system. (But it would be a mistake to dismiss it as a screed against CUPS.) The CUPS authors surprisingly acknowledged ESR's points, and he wrote a followup to the article."
Hitting them where it figuratively hurts. Ian Wilson writes with a followup to the Slashdot post earlier this month on "website thieves stealing content and designs from others, taken from silicon.com. Well, now silicon.com is reporting that it has contacted the offending site's advertisers and forced them to stop paying ad revenues - thus effectively crippling the illegal site - after all, no revenue, no reason to the run the site."
Express your appreciation with PizzaPal. Chuck writes "After you guys published the article on $20 bills exploding when microwaved, a co-worker of mine went to put his soup in the microwave and found a $20 bill in it. Too bad it was an older one, but someone around the office must have left it in there after reading your article. The co-worker then took me out to lunch. Thanks, Slashdot!"
I've seen that before... it's when I get modded -1 Flamebait within 30 seconds of posting!
Hmm, just went upstairs and checked my own microwave for cash. Nothing. Maybe I should get my dimwitted roomates to start reading Slashdot.
Kip Hawley is an idiot.
The other day, there was a bitTorrent link in the article, and I realized that I didn't have Bit Torrent installed. So when I went to download it, McAfee told me it was Spyware.
Bit Torrent is spyware?
Yet another reason for me to hate McAfee.
Hmm... put an 802.11b interface on this thing, and it won't matter that it has a trivially small amount of memory...
"Freedom means freedom for everybody" -- Dick Cheney
a co-worker of mine went to put his soup in the microwave and found a $20 bill in it.
He found a $20 bill in his soup?
At least we slashdotted thier site. So I guess there is probably a gap in there where they didn't get all the data they were looking for.
--
Live updates from Slickdeals, Tech Bargains, Bens Bargains, Got|Apex, etc..
This saddens me. I just finished implementing an md5 password hashing routine for a web application.
At least it's not production yet, so I can switch it over.
See? This is why my bosses should let me read Slashdot at work.
If they can do that, make notes using handwriting easy (no recognition required), I'd love that...
But I bet the main opponents to this would be book publishers who charge exhorbiant amounts for "new editions" where hardly anything was changed. oh well.
If we are trying to get people to move away from MD5 sums, what do we use? CRC?
There are only 10 kinds of people in this world... those who understand binary and those who don't
I had 10,000 assholes on my screen and so many being launched I couldn't stop them.
Welcome to Slashdot.
Opinions on the Twiddler2 hand-held keyboard?
Anyone wanna outsource the infrastructure and SW for the Lan party to us indians? ;-)
Jokes apart, i'd really like to fly down to USA top be a part of the lan party and see how those guys manage things.Its one thing to have a lan party with 100 ppl but using up complete subnets is one different league!
Lord of the Binges.
SHA-1 isn't really "their" message digest algorithm, they're just recommending it as a replacement for MD5, which they're trying to crack.
You have three different "MD5 sum" utilities that all give different checksums for the same data? If so, then at least two of them aren't actually MD5 utilities, in the sense that they don't compute MD5 sums. *cough*
The point is that, unlike a command tool for techies that should give them lots of choices, the goal of a GUI is to present the user with as few decision points as possible.
Remember the Macintosh dictum that the user should never have to tell the machine anything that it knows or can deduce for itself.
this is as clueful as it gets. Most app designers should heed him
Time flies like an arrow, fruit flies like a banana.
I see this every single day. The open source community (as it were) is full of people who want to use and like operating systems like Linux and BSD but are just too fucking afraid of even uttering anything that might reveal their ignorance (and I don't use that word in a negative sense) of whatever it it they're trying to accomplish with their computers.
Slashdot and USENET are full of endless threads about how easy it is to do this-or-that and if you haven't figured it out you must be supremely stupid and lazy. "What, you want it in a fucking silver plate?". Normal people (the ones not buying into open source right now) are petrified at this. They eventually either figure out how to do it ($deity bless Google) or just give up.
Without gross generalizations of course, I can't claim that everyone is this way. But there seems to be a troubling majority of zealots who are just so fantastically out there in their claims that [insert technology here] is so easy to use that even a "brain dead Windoze luser" must be able to figure it out, so they just cannot figure out why everyone hasn't dumped "M$". I mean, it's all so easy and efortless.
Maybe this will indeed be a wake up call for everyone.
ESR just jumped A LOT of points in my book. I haven't read anything so dead on in the community in ages. But add to that his level of tact and his *gasp* sympathy for the user. Wow. Definitely worth the read.
Quack, quack.
Or grab the nifty new (v1.1 released today) md5deep. Computes MD5, works recursively and most any platform too.
If you wrote code to generate the checksum(s) and it's not working then you have a problem between the keyboard and chair, not with the algorithm. That's a standard that is not OS, platform or language specific.
Be extraordinarily careful when trying to take a MD5 sum of a text file. Most operating systems will give you different file contents for a text file, depending on how you ask to open and read the file. If you have MD5 utils that aren't explicity requesting all files in binary mode, then they are being sloppy.
You also have to be careful with text files that they aren't being modified on the fly when being transferred between machines.
Thats strange -- are you feeding it the same data?
.NET -- never used it yet. Hell, I use it to pass off authentication between these languages when I can't get away with using the same language through out. All work exactly the same...and I'm not even that great of a programmer...
I have a few implementations of MD5 that I use for various apps that ALL give the same results. Sometimes you have to make sure that character sets and otherwise are being processed that same way, and it all comes out the same way.
Lets see -- I have the PHP builtin function, a perl implementation (for systems that don't have it built into the OS), a Javascript one and one that was for just plain ASP (not the
Not a flame or anything, but did you check the source for the Bittorrent client you downloaded? SpywareInfo shows there is a Bittorent client floating away with an infection of spyware.
Just for grins, I checked my machine and McAfee ( Virusscan Enterprise 7.0.0, virus defs 4341) didn't complain about ABC [Yet Another Bittorrent Client] 2.6.5 being on my machine. (Nor did AdAware 6.0.) So McAfee doesn't go after all Bittorrent clients.
So you spend all these resources to find one collision amongst 2^128 combinations.... not really that useful. Sure it is significant, but does it really bring down the entire MD5 infrastructure?
To really destroy MD5, you need to either be able to reverse the plaintext from the hash, or build a lookup table where you can get the plaintext from the hash.
Both of these seem infeasible, especially the lookup table, so things like Paypal using MD5, which the web site uses as an example, doesn't seem quite true.
for a 7.5" by 5" device with 800x600 4-tone grayscale and 10 megs they want how much??? Damn thing probably doesn't even have a decent processor, can't do 1/10th the things a 5 yr old Palm could do and they're charging $400?!? Did I warp back to 1984? Sure it's not a Mac?
Let Dell copy it and sell them for $149.
my karma will be here long after I'm gone
Apart from this, does it support any other format? I'd love to have something like this to read the countless PDF and HTML books I have, but if I had to buy them again in BBeB format, it's not quite as cool.
I frequently use MD5 in my code, for verifying a file's integrity. I do not use SHA-1 or SHA256, because they run a lot slower than MD5, without providing a realistically better guarantee that a file contains what it did at the time of its creation (if 128 bits leaves a significant chance of collision, you have bigger problems than choice of hashing algorithms... Such as how to store over a trillion yottabytes, which corresponds to one bit per 10 picograms assuming you used the entire Earth as a storage device).
Now, cryptographically, MD5 does not have the same "strength" as the SHA256. If you want to prevent tampering, you should most certainly switch to an SHA. But to just check the validity of a large block of data (such that a mere CRC doesn't suffice), MD5 works beautifully.
Additionally, I would point out to those who seem to believe finding a single MD5 collision would invalidate the whole algorithm - BS. For SHA256, going though every possible 257 bit block, you can guarantee a collision. For any hashing algorithm, that will hold true. I don't care if someone came up with a quantum hash (pulled from my posterior, since quantum-blah seems like the word of the day for magical guarantees of computational perfection), you'll still have at least one collision in N+1 bits, where the hash generates N bits.
So can we drop the SHA elitism that seems to have infected people lately? If you want to waste time in your code, go right ahead. But don't fault those of us who actually understand that, outside the realm of hard cryptography, MD5 more than suffices as an all around good hashing algorithm.
LOL. You mention in your own post that MD5 is 128 bits long. If you just restrict yourself to documents that are, say, 10mb big, that means there are 2^81920 possible plaintext documents for each MD5 hash. Granted, only some of them will look remotely like english, STILL... 2^81920 is quite enough to come up with many plaintext documents per hash. If you restrict yourself to keys
As far as I've understood it, the primary purpose is to demonstrate that cracking MD5 is realistic. If this project can then anyone with decent resources (the MD5CRK FAQ claims $100,000 would be enough) can do it. Also, additional collisions will most likely be found soon after the first one (the probability of finding collisions increases), and the data collected from the search can be used for future efforts (e.g. for analysis that might reveal actual statistical flaws in the algorithm).
MD5 is standardized and portable.
Perhaps some of the utilities you are using consider file metadata when generating the checksum?
Also beware of implicit conversions being done to your data by your I/O libraries, as other posters have noted.
DNA just wants to be free...
That is an incorrect assumption. The fundamental requirement is: It is hard (next to impossible) to find two inputs which produce the same digest (and still make sense
The message digest is usually shorter than the message, so this means that the digest contains less "information" that the message. Which means there will be more than one message for the same digest. This loss of "information" means also that you cant reverse a hash to get the original message and be 100% certain you have the right message. There is an infinite number of messages that produce that hash.
Is it really so much to ask that people learn how to use the tool they choose to use properly? Is it so much to ask that people know how to read?
When they shouldn't have to read or choose, it's lacking for an app to make them choose. In ESR's case, he shouldn't have had to make the decision as the system had all the info it needed to answer the question itself.
Yes, this takes more effort on the part of the programmer and that's probably why it's not done yet, but it's near-sighted to argue against a change that only improves the user experience. Not only does Aunt Tilly now have a good chance of getting her printer setup, I don't have to work nearly as hard reading manuals and experimenting with settings to get mine working. Why read the manual if you don't have to?
Almost forgot your comment about speed. SHA-1 is slightly slower then MD5. SHA-256 is slightly slower then SHA-1. SHA-384/512 use 64 bit operations so it is much slower on 32bit systems. In short, you concerns about speed are unfounded. Read on.
...
Run this command:
openssl speed md5 sha1
I get:
The 'numbers' are in 1000s of bytes per second processed.
type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes
md5 13426.71k 46361.18k 124663.83k 222340.64k 286203.62k
sha1 11175.12k 30058.96k 69783.42k 104107.06k 121809.96k
I also ran "time md5sum file94mb" and "time sha1sum file94mb" file 3 times in succession. The performance is much closer.
a959b7de4f11fe89ba57ecc6fe2f6a07 file94mb
real 0m1.070s
user 0m0.860s
sys 0m0.060s
a959b7de4f11fe89ba57ecc6fe2f6a07 file94mb
real 0m1.070s
user 0m0.850s
sys 0m0.070s
a959b7de4f11fe89ba57ecc6fe2f6a07 file94mb
real 0m1.071s
user 0m0.810s
sys 0m0.110s
5d926755ef975a8900b89b514feac9ded29c4477 file94mb
real 0m1.538s
user 0m1.260s
sys 0m0.060s
5d926755ef975a8900b89b514feac9ded29c4477 file94mb
real 0m1.524s
user 0m1.270s
sys 0m0.040s
5d926755ef975a8900b89b514feac9ded29c4477 file94mb
real 0m1.520s
user 0m1.280s
sys 0m0.030s
Are the MD5CRK folks trolling, smoking crack, or just not explaining themselves very well?
They "aim to disprove one of the fundamental requirements of a secure message digest: No two inputs can be found which produce the same digest - this is also known as a collision."
MD5 gives a 128-bit digest. There are more than 2^128 possible messages. Of course there are collisions. What MD5 claims is that the difficulty of coming up with two messages having the same message digest is on the order of 2^64 operations, and that the difficulty of coming up with any message having a given message digest is on the order of 2^128 operations.
No digest algorithm can claim to be free of collisions; they are many-to-one mappings.
Tom Swiss | the infamous tms | my blog
You cannot wash away blood with blood
-Cool
/back story of your choice.... Moderate as appropriate.
-Duh!
-huh?
-Whoa!
Please feel free to apply to comment of your choice, to the
> to...be able to reverse the plaintext from the hash
THE plaintext? Firstly, there cannot be only one plaintext. By the pigeonhole principle, a few byte sum cannot be unique for all multi-megabyte texts.
Besides, if that were possible, MD5 would not be destroyed; it would become the world's best compression.
ESR says, "Let's go back to the queue type selection screen. Remember that one? It looks like this: Locally connected, Networked CUPS (IPP), Networked Unix (LPD), Networked Windows (SMB), Networked Novell (NCP), Networked JetDirect". He then goes on to say that all of this should be autodetected and then the irrelevant options grayed out. According to him, each host do a Christmas tree scan (!!) of the local network to see what printer types to prompt for.
:)
:)
First of all, he'd better stay the hell away from my network. I thank goodness that no other (non-script-kiddie) application on this planet performs unprompted scans like this. DHCP, of course, doesn't count.
Second, what if the printer is currently down? Or I'm configuring a machine to be installed offsite? I can think of any number of scenarios where I'd want to configure a network printer that isn't currently on the network.
A program should NEVER think that it's smarter than the user. What if CUPS doesn't detect "wvlan0" as a network interface? Well, it would gray out all the network printer options. But that's clearly wrong -- the user *knows* that the machine is networked. If CUPS allowed him to configure the network printer, everything would just work. Note that CUPS probably should put up a warning dialog "Warning: I could not detect a network -- do you want to continue," but it should not prevent or restrict anything.
ESR's solution relies on too much magic and will cause support nightmares. It is too system-dependent -- it might work on Red Hat, but it'll probably break on SuSE. Or an ARM-based machine. Or a token ring network. Etc. And when it breaks, the user will be surprised and have no other recourse than to consult the documentation.
Incidentally, graying something out is almost always wrong because it gives no indication as to why it's grayed out! You should let the user select it, then put up an informative dialog telling the user that what he's doing doesn't make sense, and what he or she might do to fix it. Always, always, always tell WHY.
Yes, the CUPS UI is flawed ("client-error-forbidden! client-error-forbidden!"), but ESR's proposal is even worse. It's a measly six-item menu! If Easy Software did try to implement it, after a ton of programmer time they'd have an interface that is more surprising, less informative, and more fragile. Not a step in the right direction.
The proper way to fix this unfriendly menu is to create a wizard The first page would allow you to select a locally-connected printer or, if there are no unconfigured local printers, a network printer (possibly launching a Samba browser to help). Wizards are great for reducing perceived complexity without reducing functionality.
Creating a good user interface is hard. I think that ESR just proved this.
[100% ISO 646 Compliant]
SVM, ERGO MONSTRO.
Peachy. Where were you going to put the lookup table for that? 2^81920 is on the order of 10^25000. If you could store one of those documents on an atom (attach it with a little dab of glue, okay?) you'd have enough plaintext documents for every atom in this universe...and for every atom to have its own universe of attached atoms...and still have enough documents to be short several orders of magnitude of storage space. Generating the table is left as an exercise for the reader. Cheers.
~Idarubicin
By my calculations, at the current rate they'll take over 500 years to produce a collision. They need about a hundred times as many people on board to get anywhere.
1 9.78646399116343804161
The sum I did is
sqrt(-l(0.5)*2*2^128)/(1.325*10^9*86400*365)
5
N=2^128 is the space they're looking for a collision in. The expected number of collisions found after k items have been produced is very close to k^2/2N, so the probability zero have been found is exp(-k^2/2N) by the Poisson distribution. Assume exp(-k^2/2N) = 0.5 and solve for k, then divide by their declared rate of 1.325 gigaMD5s a second.
I don't know whether this inclines me to give the whole thing up or to climb on board. The latter is probably more fun.
Incidentally, the algorithm they're using to do the search efficiently is pretty cool. Paul C van Oorschot and Michael J Wiener, Parallel Collision Search with Cryptanalytic Applications (pdf)
Xenu loves you!
That is bullshit. Of course two inputs can be found which produce the same message digest. This is the pigeonhole principle. Now the MD5CRK developers seem like smart people, and so it's more likely that they just haven't explained it very well.
They go on to say
But I don't see what that would achieve either: two strings of gibberish that happen to have the same MD5 sum. Find a way to produce two documents which both have meaning (perhaps two pieces of source code, or two different school reports) and have the same signature, and that would be impressive.
-- Ed Avis ed@membled.com
For all those interested in the MD5 signing of a message and how "impossible" it is - take a look at www.cryptool.org and the demonstration under "Individ. Procedures" -> "Attack on the hash value of a signature". You may be (unpleasently) surprised about how easy it is to match two completely different documents to have the same MD5.
Two wrongs may not make a right, but three
Setting up a printer in Linux was one of the first things I did after I figured out how to install it, and surprise surprise all i had to do to get it working was, wait for it, READ THE MANUAL.
And in the Windows, installing a network printer goes like this: Select 'add new printer', click next, check 'network printer', click next, click next, select the printer from the list, click next, click finish, admire the test page printed out on the remote printer. Windows user is done before Linux user read the first page of the manual.
Do you for a second believe that Linux way is better in this respect?
Is it really so much to ask that people learn how to use the tool they choose to use properly? Is it so much to ask that people know how to read?
Joe Q. User (you know, the one Linux needs to win over in order to establish world domination) answers: Yes, and yes. I want to install a printer, not read something. If I wanted to read something, I'd go to the library.