Comments on: What Is DES and 3DES? http://azio.org/2006/10/19/what-is-des-and-3des/ return of the men in black Thu, 11 Mar 2010 15:52:57 +0000 http://wordpress.org/?v=2.7.1 hourly 1 By: Yahoouj http://azio.org/2006/10/19/what-is-des-and-3des/comment-page-1/#comment-44317 Yahoouj Tue, 23 Feb 2010 07:18:43 +0000 http://azio.org/2006/10/19/what-is-des-and-3des/#comment-44317 Really good work about this website was done. Keep trying more - thanks! Really good work about this website was done. Keep trying more - thanks!

]]> By: What Is DES and 3DES? « Security News http://azio.org/2006/10/19/what-is-des-and-3des/comment-page-1/#comment-6997 What Is DES and 3DES? « Security News Tue, 16 Oct 2007 15:50:56 +0000 http://azio.org/2006/10/19/what-is-des-and-3des/#comment-6997 [...] read more | digg story [...] [...] read more | digg story [...]

]]> By: Keith http://azio.org/2006/10/19/what-is-des-and-3des/comment-page-1/#comment-75 Keith Fri, 20 Oct 2006 12:09:14 +0000 http://azio.org/2006/10/19/what-is-des-and-3des/#comment-75 There are also methods such as <a href="http://www.neohide.com" rel="nofollow">BlowFish</a>. In whatsoever, it is always useful to use 3DES rather than DES. There are also methods such as BlowFish. In whatsoever, it is always useful to use 3DES rather than DES.

]]> By: azio http://azio.org/2006/10/19/what-is-des-and-3des/comment-page-1/#comment-69 azio Thu, 19 Oct 2006 22:56:39 +0000 http://azio.org/2006/10/19/what-is-des-and-3des/#comment-69 Hey Saqlib, Thanks for your response on my blog, I thought I'd reply here and on my blog, Indeed you are correct. I think that what you mean is that the 3TDES has a much likelier chance of collision or success from linear cryptanalysis , and could, in the right circumstances be as insecure as DES, perhaps. I would add these details to my blog but I think they stand out quite well in your comment! Best Wishes, Azio Hey Saqlib,
Thanks for your response on my blog, I thought I’d reply here and on my blog, Indeed you are correct. I think that what you mean is that the 3TDES has a much likelier chance of collision or success from linear cryptanalysis , and could, in the right circumstances be as insecure as DES, perhaps.

I would add these details to my blog but I think they stand out quite well in your comment!

Best Wishes,

Azio

]]> By: saqib ali http://azio.org/2006/10/19/what-is-des-and-3des/comment-page-1/#comment-68 saqib ali Thu, 19 Oct 2006 21:13:28 +0000 http://azio.org/2006/10/19/what-is-des-and-3des/#comment-68 very good. but why does 3TDES (3 Distinct Keys) has a effective key-length of 112-bit ??? Understanding this is important to understanding why even 3TDES is considered insecure, theoretically Here is the explanation. ---------------- So, triple DES involves three keys, K1, K2, K3. Write single-DES encryption with a key K and plaintext block x as E(K, x), and decryption as D(K, x). Triple DES encryption is E(K3, D(K2, E(K1, x))). Suppose you're given a plaintext block x and corresponding ciphertext y. For each possible K3, compute D(K3, y), and store the result in a table. This takes about 2^56 work, and uses 2^56 blocks of memory. Now, for each pair K1, K2, compute D(K2, E(K1, x)). If this matches one of the values in the table, find the corresponding K3, and test the whole key against some other plaintext/ciphertext pairs. Continue until you're done. This step takes no extra memory and requires 2^112 time. -------------------- saqib http://www.full-disk-encryption.net very good. but why does 3TDES (3 Distinct Keys) has a effective key-length of 112-bit ???

Understanding this is important to understanding why even 3TDES is considered insecure, theoretically

Here is the explanation.
—————-
So, triple DES involves three keys, K1, K2, K3. Write single-DES encryption with a key K and plaintext block x as E(K, x), and decryption as D(K, x). Triple DES encryption is E(K3, D(K2, E(K1, x))).

Suppose you’re given a plaintext block x and corresponding ciphertext y. For each possible K3, compute D(K3, y), and store the result in a table. This takes about 2^56 work, and uses 2^56 blocks of memory.

Now, for each pair K1, K2, compute D(K2, E(K1, x)). If this matches one of the values in the table, find the corresponding K3, and test the whole key against some other plaintext/ciphertext pairs. Continue until you’re done. This step takes no extra memory and requires 2^112 time.
——————–

saqib
http://www.full-disk-encryption.net

]]> By: Azio’s Computer Log » About: Linear CryptAnalysis http://azio.org/2006/10/19/what-is-des-and-3des/comment-page-1/#comment-66 Azio’s Computer Log » About: Linear CryptAnalysis Thu, 19 Oct 2006 19:25:49 +0000 http://azio.org/2006/10/19/what-is-des-and-3des/#comment-66 [...] History Mitsuru Matsui discovoered linear cryptanalysis methodology , who first applied the technique to the FEAL cipher (Matsui and Yamahgishi) in 1992. Matsui published an attack on the DES algorotihm also, as mentioned in a previous azio.org article:what is DES and 3DES. [...] [...] History Mitsuru Matsui discovoered linear cryptanalysis methodology , who first applied the technique to the FEAL cipher (Matsui and Yamahgishi) in 1992. Matsui published an attack on the DES algorotihm also, as mentioned in a previous azio.org article:what is DES and 3DES. [...]

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