Talk:Data Encryption Standard

message: * I would like to make a formal request to add http://www.celtickane.com/programming/ to the external links section of this page. It is my own website, so I wouldn't like to add it myself, but I would prefer that someone else review the website, and make the decision to add it. It contains a basic example of DES encryption in C++, which would be useful for someone who is wanting to program a DES encryptor. --Sugarskane 04:00, 20 July 2006 (UTC)
replies: text: *Hi, you already did add the link yourself  but I think this article should not be a link farm for implementations, since there are dozens to choose from. We do link to Helger Lipmaa's portal-like page about DES , which itself links to quite a few DES implementations. You might contact Helger and ask him to add your implementation to his list. In general, please take a look at WP:EL, particularly WP:EL#Links_normally_to_be_avoided item 3, since I see you've added your links to quite a few other Wikipedia articles, which could be considered spamming. Phr (talk) 06:11, 20 July 2006 (UTC)

text: Any of the articles I've added have been removed -- which is why I'm adding a request to the talk page instead. I will contact Helger -- thank you. --Sugarskane 14:27, 20 July 2006 (UTC)
replies: text:  While your computing related articles are well-written, I don't think they are unique or notable enough to merit inclusion on any of the pages that you've added them to. There are thousands of similar articles out there. While you may be able to find examples of programming-related links on Wikipedia that are non-notable, it just means that someone hasn't cleaned them up yet. Because techies rely on the web for quick info on programming topics, programming articles are hot targets for people looking for Google Adword revenue. On one Yahoo! group that I subscribe to, a user kept posting a link J2EE tutorial that he argued was relevant. A little research revealed that he'd simply cut-and-pasted the content from Sun Microsystems's site and threw it up on his site. I realize your material is original, but as I said, I don't think it's particularly notable or unique. OhNoitsJamie Talk 15:20, 20 July 2006 (UTC)
thread_title: Request for external link addition

message: There should some discussion and a link pointing out the remarkable simple method, developed at Princeton, of pulling the crypto key out of memory. They merely spray the RAM chips with an upside down can of Dust Off to delay the decay of latent data, then insert a USB key with their extractor program, and boom! they have the keys.
http://news.cnet.com/8301-13578_3-9876060-38.html —Preceding unsigned comment added by 64.134.22.157 (talk) 22:36, 11 March 2010 (UTC)
replies: text: That method has nothing to do with the DES algorithm - it would apply to any memory contents, regardless of whether the memory was a crypto key, or the algorithm that the key was used for. Hence it does not belong in an article about DES. Mitch Ames (talk) 09:18, 12 March 2010 (UTC)
replies: text:  Cold boot attack describes the general attack - without mentioning that the latency can be extended by cooling the chips. (Cold boot in this case refers to the power cycle, not the temperature.) Mitch Ames (talk) 09:23, 12 March 2010 (UTC)
thread_title: ==

message: you can get rid of all those smalls with a style="font-size:85%" or something, can't you? - Omegatron 01:04, Mar 16, 2005 (UTC)
: Yes, you can, thanks for the tip! — Matt Crypto 12:38, 16 Mar 2005 (UTC)
thread_title:  table 

message: Hi. A nicely written page. This might sound a bit pedantic but could I question the wording of "DES is now considered insecure because a brute force attack is possible..."
As I understand it a brute force attack is always possible on virtually all encryption algorithms (exception of one time key pads) merely that with a useable algorithm it is not practical within the useful timelife of the data. Thus 56-bit DES became unuseful because it is now crackable whilst the data is still sensitive.
Any thoughts? --Grapeswrath 03:00, 20 September 2005 (UTC)
replies: text: Yeah, I don't mind replacing "possible". I'm unsure about an unqualified "practical", though, because it's still quite an effort to do brute force over 56 bits, even in 2005. — Matt Crypto 11:36, 20 September 2005 (UTC)
replies: text: How about something like "feasible with todays hardware". bit wordy....--Grapeswrath 12:54, 20 September 2005 (UTC)

text: Or just "possible within 24 hours"....--Grapeswrath 13:11, 20 September 2005 (UTC)

text: Re that last point: that's the test of whether a cipher is well constructed. It's a necessary but not sufficient condition for being secure. The other part of the requirement is that brute-force attack has to be sufficiently hard. (Definition of "sufficiently" is something like "not economically feasible for very well funded attackers, over the useful life of the data to be protected, with a decent margin of safety".) DES has clearly failed that test for some time. (In fact, Diffie and Hellman credibly argued that it failed that test from Day One.) As for how to describe it, I see absolutely nothing wrong with "practical" -- it takes a modest investment in hardware to build a machine that can do it in a few days. Paul Koning 19:41, 6 July 2007 (UTC)
thread_title:  Brute Force 

message: Matt C: I agree that Biham and Shamir attacked full-round DES later, but it's significant that they rediscovered differential cryptanalysis earlier. If DC was one of IBM's factors in the DES design, it seems fitting to include when it was first "publicly" discovered. Mmernex 14:23, 16 May 2007 (UTC)
replies: text: Oh, absolutely—it was just that we needed to be accurate about what happened in 1990 and 1992. Having both dates is ideal. — Matt Crypto 18:10, 16 May 2007 (UTC)
thread_title: Biham, Shamir & DES

message: DES modes are important. Not going to accept casual deletions from Matt Crypto.
: Think of it this way: should we include a section on modes of operation in each and every article on a block cipher? Clearly not. The sensible solution is deal with it in a separate page. — Matt Crypto 01:20, 30 October 2005 (UTC)
replies: text: You haven't really answered the question. Would you have us include a section on all the modes in each and every block cipher article? The issue is where it is best to include a lengthy discussion on general-purpose block cipher modes. ECB, OFB, CBC, CFB and CTR modes can be used by any block cipher, not just DES. General stuff on modes is best put in the block cipher modes of operation article. If we include any information on modes here, it should be specific details concerning DES and modes that aren't more widely applicable to block ciphers in general. — Matt Crypto 02:03, 30 October 2005 (UTC)

text: While your "many tests on security and cryto" do sound impressive, I'm afraid your argument is not particularly convincing. We do already say that "Like other block ciphers, DES must be used in a mode of operation if applied to a message longer than 64 bits. FIPS-81 specifies several modes for use with DES, including one for authentication [2]. Further comments on the usage of DES are contained in FIPS-74". Now, I would be very happy to see additional specific details about DES and modes (such as what modes are specified in the FIPS publications and so forth), but to go into detail about basic general principles of block cipher usage is overkill in this article. Moreover, I'm afraid your explanation is confusing and incorrect in parts, particularly the ECB paragraph, which confuses the action of the mode with the operation of the DES primitive itself. — Matt Crypto 02:22, 30 October 2005 (UTC)

text: *Sigh* I'll come back to this tomorrow, if I have time. It's discouraging that you've stopped presenting any arguments and started with comments about "bullying" and boasting about how experienced you are with DES and how many textbooks you have. Good, but make use of your experience and read your textbooks. You've quite clearly not explained the ECB mode correctly at all, confusingly adding a fudged explanation of the main DES algorithm itself. You wrote that, "ECB is applied to 64-bit blocks of plaintext to provide 64-bits of ciphertext. The 64-bit input vector is divided into two 32-bit blocks called the Right Block and the Left Block, and then recopied to form two 48-bit blocks. Each of these two 48-bit blocks are XORed with a 48-bit encryption key. Because ECB does not use chaining, patterns in the ciphertext can be detected; hence, ECB is not used to encrypt large blocks of data. — Matt Crypto 02:44, 30 October 2005 (UTC)

text: Matt is right, these explanations are totally inappropriate and are redundant for this article. You have ceased addressing his point and have started engaging in some kind of strange book-based pissing contest. I'm just going to remove them and keep them out, I'm assuming everyone else will revert along with me, there's no point in wasting energy arguing this further. Nathan J. Yoder 17:34, 1 November 2005 (UTC)
thread_title: Should include DES modes

message: Please see Talk:DES for a discussion related to this article. Peyna 16:16, 3 December 2005 (UTC)
thread_title:  Disambig 

message: I left a note asking Cyde to run his conversion bot to turn the inline references to footnotes. I hope no one minds. All featured articles are supposed to use footnotes now, I think. Phr (talk) 08:12, 14 July 2006 (UTC)
replies: text: I converted 4 inline references into unformatted URL footnotes today. The article is 100% footnotes although there's room for format improvements. – Conrad T. Pino (talk) 03:07, 11 April 2008 (UTC)
thread_title:  Inline references 

message: Where was DES used and where is it used now? In mobile phones, pay per view, police radios?
Velle 10:45, 22 August 2006 (UTC)
thread_title:  Applications 

message: What do you think about a section or link(s) to open source software implementations? Daniel.Cardenas 17:35, 16 June 2007 (UTC)
replies: text: Perhaps, but one concern is that there's been lots of crypto pages (MD5, SHA, AES etc) that have been spammed full of links to gazillions of implementations, with the result that people are a bit reluctant to include links to any at all. — Matt Crypto 18:26, 16 June 2007 (UTC)
thread_title: Open source software implementations?

message: I just read a paper by E. Biham regarding his key-collision attack. (Information Processing Letters 84 (2002) 117-124)
Titled: "How to decrypt or even substitute DES-encrypted messages in 2^28 steps"
I don't see mention of this in the article, other than passages discounting linear and diff. cryptanalyis as "impractical" (an arbitrary quantifier). Biham's latest method described requires 2^28 known blocks, which is not completely impractical, only marginally.. my point being I'd like to add mention of this somewhere.--Raidfibre 18:17, 6 July 2007 (UTC)
thread_title: Biham key-collision attack

message: What sort of a "Featured Articel" is this!? An (admittedly) minor pastel shaded box, but worse, "citation needed"'s in many places, and more so, some unattributed direct quotations from people! 68.39.174.238 03:19, 31 August 2007 (UTC)
replies: text: Wikipedia had very lenient citation/attribution requirements back when this was featured; the article has changed little since. -- intgr #%@! 07:03, 31 August 2007 (UTC)

text: Blast it? -- What, like, with a Directed-energy weapon? ;-) Yeah, as Intgr points out, Wikipedia's standards have changed over the last 3 years, and it's a good thing that people expect the highest standards from Featured Articles. It shouldn't be too much work to bring this article in line with modern referencing requirements, at least. — Matt Crypto 08:08, 31 August 2007 (UTC)
replies: text: I know that, but such articels would usually be found out and delisted under the new regime, EG MKULTRA got delisted a while ago for those reasons. 68.39.174.238 14:17, 2 September 2007 (UTC)
thread_title:  Blast it! 

message: 80.230.111.1 13:09, 5 November 2007 (UTC)
thread_title:  Confusion / Diffusion 

message: Hi, I’d like to suggest newly created webpage () which comprises a presentation and an encoding application. The first one is a step-by-step presentation of DES scheme. The latter is a fully functional application which encrypts and decrypts messages of any size.
At the beginning of the presentation users can fill in appropriate form fields (Message field and Key field) but to their convenience it’s not necessary – exemplary data is provided.
The presentation is divided to stages which perfectly reflect structure of the process. First of all sixteen 48-bit long subkeys are created from the given key. This part is called Key Schedule and is composed of few stages. Next, the actual encryption/decryption process ensues.
Interface of the presentation is constructed in the way, which makes possible familiarizing readers with principles and output results of every step of the DES algorithm and after that moving on to the subsequent stage.
Besides above-mentioned presentation everyone can try out another utility. It is an application which encodes and decodes messages of any size, in theory of course, because server capabilities are limited. In this case size of given message can’t exceed 5000 characters.
I’ve found over the Internet few DES encrypting programs, but none of them works properly. Few of them operate solely with English alphabet. Another few force users to provide data of a specific size only. Our application is devoid of those constraints. Thus, any person can use it for private, or not, purposes to encrypt and decrypt messages of any size and in any language. —Preceding unsigned comment added by Lukasz Tlomak (talk • contribs) 15:24, 13 March 2008 (UTC)
thread_title:  External link suggestion 

message: This link says that some criteria for designing S-Boxes come from a paper by Coppersmith, but Douglas Stinson's Cryptography theory and practice talks about a 1976 speech or document by the NSA or NIST (actually the reference to NIST is a footnote in the French translation). I don't know whether these data are in the sources listed in the article. I think it's important information which should be added (if we have a reliable source). Apokrif (talk) 04:07, 2 June 2008 (UTC)
thread_title:  Criteria for building S-Boxes 

message: DES exhibits the complementation property, namely that
:E_K(P)=C \Leftrightarrow E_\overline{K}(\overline{P})=\overline{C}
where \overline{x} is the bitwise complement of x. E_K denotes encryption with key K. P and C denote plaintext and ciphertext blocks respectively. The complementation property means that the work for a brute force attack could be reduced by a factor of 2 (or a single bit) under a chosen-plaintext assumption.
Is this true? If I have some known plaintext M and I give it to an external system and receive the crypted text C how does it reduce my search space to know that DESk^(M^) = C^? I can see how it would reduce the search space if we did not know M or k. But considering we do know M we must still check all k (whether we check this by inverting everything or not it does not matter).
129.78.64.100 (talk) 05:13, 4 June 2010 (UTC)
replies: text: Presumably because the inversion takes negligible time compared to the computation of DESk(P)? When the number of DES computations is cut in half, the total work is effectively reduced by a factor of two (I would think). decltype (talk) 06:57, 4 June 2010 (UTC)
thread_title:  Minor Cryptanalytic Properties 

message: The article currently states that
"under a chosen-plaintext assumption, the data complexity can be reduced by a factor of four (Knudsen and Mathiassen, 2000)."
In the paper in question ("A Chosen-Plaintext Linear Attack on DES"), Knudsen and Matthiassen describe Matsui's attack as needing 2^44 known plaintexts, compared to the 2^42 chosen plaintexts of their attack. However, in "The First Experimental Cryptanalysis of the Data Encryption Standard", Matsui states that the attack needs 2^43 known plaintexts. (Matsui also refers to the attack as having an 85% success rate, as opposed to the 78% mentioned by Knudsen and Matthiassen.)
Unless K+M are implicitly claiming Matsui's calculations for the probability of success with 2^x known plaintexts were wrong, I don't see how the article can claim more than a twofold improvement in data complexity through the use of chosen plaintexts.144.32.126.12 (talk) 22:06, 5 January 2011 (UTC)
thread_title:  Reductions in linear cryptanalysis data complexity under the chosen-plaintext assumption 

message: In the image DES-main-network.png it shows that in the last stage (the output from the F-networks) remain of the "left" and "right" after passing through the F-network. In the version I wrote the last bug I detected was recombining the output in the same order, although it seems that it has to be switched (the left hand side makes up the last 32 bits and the right hand side makes up the first 32 bits) should there be a final cross over shown at the bottom of the image? Here's the part of my code that I'm talking about:
//Split input into two halves
            bool[] left = new bool[32];
            bool[] right = new bool[32];
            for (int i = 0; i < 32; i++) {
                left[i] = data[i];
                right[i] = data[i + 32];
            }
            //Pass though F-function
            bool[] f;
            //Round 1
            f = Feistel(right, subKeys[0].Key);
            left = Functions.XOR(left, f);
            //ETC
            
            //Round 16
            f = Feistel(left, subKeys[15].Key);
            right = Functions.XOR(f, right);
            //Recombine left and right
            bool[] result = new bool[64];
            for (int i = 0; i < 32; i++) {
                result[i] = right[i];
                result[i + 32] = left[i];
            }
--Simpsons contributor (talk) 18:29, 1 July 2011 (UTC)
replies: text: I've just remembered to respond to this (sorry it took half a year) but after an even number of rounds the original "left" if on the "right" and so that is the apparent flip. It was the copying to the final array thaw was confusing things. --Simpsons contributor (talk) 03:26, 22 December 2011 (UTC)
thread_title: Final switch?

message: Hello, In the chapter 2.1 (Overall structure), at the third paragraph, we can see "After the final round, the halves are swapped;".
But on the "Figure 1", I don't see this last swapping.
I am not very good in crypto, I came on this page to learn, so may be I didn't understand very well.
Thanks for who will analyse that :)
Bye  — Preceding unsigned comment added by 93.20.247.38 (talk) 11:51, 5 October 2016 (UTC)
thread_title:  is the Figure 1 correct ? I think that the final swapping is missed (before the FP) 

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thread_title:  External links modified 

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thread_title:  External links modified 

message: The section that talks about the NSA's role in modifying DES uses this essay for its source, but the essay cites no sources and the link to where the essay was originally found is dead. Are there any  verifiable sources for the claims about NSA involvement that this source covers?  — Preceding unsigned comment added by 139.62.13.235 (talk) 14:40, 18 September 2018 (UTC)
thread_title:  Unverifiable Source for NSA's role in DES? 

message: From the aricle:
Note that the two citations are visually identical but reference different URLs. I was not able to find the quoted passage in either of the linked documents. I don't understand what the "differently redacted" comment is supposed to mean here, in any case, I don't find the quote to be substantiated. 138.246.3.123 (talk) 14:43, 1 July 2022 (UTC)
thread_title:  Misattributed citation?