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| | Known Plaintext Attack |
 | | The known plaintext bytes are the inputs of the update_keys function, and the derived key3's are the outputs. | | | In this case, 13 known plaintext bytes are required for the whole attack, and the complexity of analysis is 2^{38}. | | | This known plaintext attack breaks the cipher using 40 (compressed) known plaintext bytes, or about the 200 first uncompressed bytes (if the file is compressed), with complexity 2^{34}. |
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http://www.svn.net/mycal/junk/attack.htm
(1999 words)
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| | The Story of Combiner Correlation: A Literature Survey |
| | Attack: Klapper and Goresky show that the summation cipher is in fact the addition of "2-adic" numbers, and present a sequence reconstruction algorithm analogous to Berlekamp-Massey. | | | Attack: Siegenthaler addresses the situation of a single LFSR which is tapped at several places to provide multiple inputs for a nonlinear combining function. | | | Attack: Chepyzhov and Smeets present a new algorithm for LFSR state recovery from noisy data. |
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http://www.ciphersbyritter.com/RES/COMBCORR.HTM
(6188 words)
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| | Zip, PKZip, Winzip Password Recovery Service |
| | A known plaintext attack is accomplished by using an unencrypted version of one of the files in a zip archive to decrypt the others. | | | The first way is by performing a known plaintext attack. | | | In this attack, every possible combination of characters is tested against the password until a match is found. |
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http://www.pwcrack.com/zip.shtml
(650 words)
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| | Cryptanalysis of MultiSwap |
| | As for the output, since k11 is known, given c0 one can partially decrypt to find the intermediate value computed immediately after the multiplication by k10. | | | We will present the attack assuming that s0=s1=0, but it also works when they are non-zero but known: just use x0=-s0 instead of x0=0. | | | But since k6 is known, an attacker can control the input to the cipher fragment starting with multiplication by k7. |
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http://www.cs.berkeley.edu/~rtjohnso/multiswap
(1884 words)
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| | SecuriTeam.com ™ - Yet another Plaintext Attack on ZIP's Encryption Scheme (WinZIP) |
| | Attacks to ZIPs with less than 3 files might be also possible because in WinZIP the two CRC most important bytes are stored within the 12 "random" numbers. | | | Getting plaintext is even more difficult because the plaintext is in its compressed form and a minimal change on the data would represent a great alteration, so if we did not know the full file content included on zip file we could not do anything. | | | The ZIP format is one of the most widely used compression/archival programs on computers systems. |
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http://www.securiteam.com/securitynews/5LP0A0096O.html
(929 words)
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| | Known-Plaintext Attack Against a Permutation Based Video Encryption Algorithm - Slagell (ResearchIndex) |
| | We demonstrate that this particular algorithm is vulnerable to a known-plaintext attack, and hence its use should be carefully considered. | | | Known Plaintext Attack Against a Permutation Based Video Encryption Algorithm,2002 Available at http://www.slagellware.com http://citeseer.ist.psu.edu/slagell04knownplaintext.html More | | | Algebraic Attacks on Combiners with Memory and Several Outputs - Courtois (2003) |
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http://citeseer.ist.psu.edu/slagell04knownplaintext.html
(403 words)
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| | Cryptography:Meet In The Middle Attack - Wikibooks |
| | However, given sufficient storage, you can reduce the effective key strength of this to a few bits larger than the largest of the two keys employed, as follows. | | | to the ciphertext for each possible key in turn, comparing the intermediate plaintext to the hash table calculated earlier. | | | An example of such a compound system is 3DES. |
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http://en.wikibooks.org/wiki/Cryptography:Meet_In_The_Middle_Attack
(412 words)
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| | Cryptography FAQ (04/10: Mathematical Cryptology) |
| | In intuitive terms a (passive) attack on a cryptosystem is any method of starting with some information about plaintexts and their corresponding ciphertexts under some (unknown) key, and figuring out more information about the plaintexts. | | | If n is big enough that only one key works, this attack will succeed on valid inputs all the time, while it will produce correct results only once in a blue moon for random inputs. | | | Such systems, where the same key value is used to encrypt and decrypt, are also known as ``symmetric'' cryptoystems. |
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http://www.faqs.org/faqs/cryptography-faq/part04
(1368 words)
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| | Known-Plaintext and Compression |
| | If cryptanalytic attack was the /only/ consideration, correspondingly less effort should be put into eliminating known plaintext - but it is only one of a number of possible ways that the attacker can reduce the work required for a brute force search. | | | The problem is the improved ability to analyze a ciphering function when one has both the input to -- and output from -- that function (this is known-plaintext, as opposed to having ciphertext-only). | | | Consider, for example, the case where there is no known attack on the cypher, but the key generator is broken. |
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http://www.ciphersbyritter.com/NEWS6/KNOWNPLN.HTM
(16818 words)
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| | The Risks Digest Volume 16: Issue 39 |
| | The attack will work with versions 1.1 or 2.xx of PKZIP and other programs using the same algorithm. | | | My attack is an improvement on a known plaintext attack described in a paper by Biham (unpublished work) that takes 2^38+ operations. | | | I've written code for all steps of the attack; a version written in C with a few optimizations in inline assembly runs in less than a day on my '486. |
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http://catless.ncl.ac.uk/Risks/16.39.html
(2988 words)
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| | Partial attack on CBCC |
| | This latter point is connected in the nature of scenarios where you can postulate chosen plaintext in the context of an otherwise secure system depending on integrity. | | | In the outer layers of the loop, however, he may discard unpromising possibilities based on seeing the hypothetical decrypts of the early blocks and not spend time seeking good but useless decrypts. | | | He can decide, based on this corrupted value and other information in the packet, whether to make the substitution. |
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http://www.cap-lore.com/Crypto/CBCCattack.html
(1030 words)
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| | Monoalphabetic Substitution |
| | Once we have found all possible matches, we can use a chi-squared statistic to determine which one is the most likely match for the known plaintext. | | | The Applet below is programmed to illustrate this codebreaking process. | | | Here's an example of how this codebreaking process might take place. |
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http://math.ucsd.edu/~crypto/java/EARLYCIPHERS/Monoalphabetic.html
(719 words)
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| | [No title] |
| | plaintext attack: some problems when plaintext file is in subfolder Version 3.50 beta 1 ------------------- ! | | | wrong tooltip for tray icon on known plaintext attack + displaying long numbers and date/time according to regional settings + plaintext attack using binary file Version 3.0 beta 3 (19/01/2000) ------------------------------- ! | | | status/prograss bar overlapping under Windows XP Version 3.51 ------------ + "end at" option + partial plaintext attack: enter the known bytes as decimal values (in addition to HEX) ! |
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http://www.elcomsoft.com/AZPR/whatsnew.txt
(873 words)
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| | LWN: A weak cryptoloop implementation in Linux? |
| | I wonder if it is would be possible to store such 'known plaintext' as real plaintext, thus making it useless for an attacker. | | | But the alternative to just XOR every disk block with a 4096-byte random string (and store that string somewhere, in plaintext) before passing it to the loopback device will work to stop the attack described here. | | | One other way around the problem is Cipher Block Chaining (CBC), where the output of each block is dependent on all prior blocks, as well as a randomly chosen initial vector (IV). |
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http://lwn.net/Articles/67216
(3270 words)
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| | Russian Password Crackers |
| | A GUI utility, optimized for Pentium II/III processors, supports brute-force, dictionary and known-plaintext attacks, multilanguage interface. | | | A GUI utility, optimized for Pentium II/III processors, supports brute-force, dictionary attacks, multilanguage inferface. | | | A command-line utility, optimized for Pentium/Pentium II/III processors, supports brute-force, dictionary attacks. |
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http://www.mirrors.org/linux/www.password-crackers.com/crack.html
(549 words)
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| | What are plaintext and ciphertext? |
| | Plaintext, also known as cleartext, is usable data. | | | A cryptanalyst in possession of a piece of plaintext and the resulting ciphertext can attempt to mount a known plaintext attack. | | | Encryption is the process of turning plaintext into ciphertext. |
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http://www.tech-faq.com/plaintext-ciphertext.shtml
(150 words)
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| | Cpt Sc 427/527 Computer Security |
| | Brute-force attack: An exhaustive search of the key space for a conventional encryption algorithm. | | | If there are several matches, each of these can be tried against the full ciphertextto determine the right one. | | | The defense against brute force key attacks is the length of the key which can be from 40 to 168 bits with longer being better. |
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http://www.tricity.wsu.edu/htmls/cs427/public_html/Hw6_01sol_v1.htm
(458 words)
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| | : Advanced ARJ Password Recovery, review at WorldSSP.net |
| | Supports the customizable brute-force attack, effectively optimized for speed; dictionary-based attack, and very fast and effective known-plaintext attack. | | | Supports the customizable brute-force attack, effectively optimized for speed (about two million passwords per second on modern CPUs); dictionary-based attack, and very fast and effective known-plaintext attack. | | | Supports the customizable "brute-force" attack, effectivelyoptimized for speed (about two million passwords per second on modernCPUs); dictionary-based attack; and very fast and effectiveknown-plaintext attack. |
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http://www.worldssp.net/webinfo.asp?proid=2255
(312 words)
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| | sci.crypt: Re: Known Plaintext Attack Against Blowfish |
| | In reply to:(deleted message) No One: "Known Plaintext Attack Against Blowfish" | | | The best known attack on Blowfish can determine if a weak key is used |
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http://www.derkeiler.com/Newsgroups/sci.crypt/2004-04/0985.html
(315 words)
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| | Perfect Encryption |
| | The key comes in the form of a file that contains nothing but perfectly random, independent bytes. | | | I'm sure you would like to see the algorithm now. | | | Where C is the ciphertext, P is the plaintext, K is the pad (key), i is the index into the file. |
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http://members.aol.com/PrismRisirch/perfectencryption/perfectencryption.html
(586 words)
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| | Known-plaintext attack - Wikipedia, the free encyclopedia |
| | Then using some publicly available software they can instantly calculate the key required to decrypt the entire archive. | | | For example, an attacker with an encrypted ZIP file needs only one unencrypted file from the archive which forms the "known-plaintext". | | | Encrypted file archives such as ZIP are also very prone to this attack. |
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http://en.wikipedia.org/wiki/Known-plaintext_attack
(204 words)
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| | What is a known plaintext attack? |
| | A known plaintext attack is an attack where the cryptanalyst has access to the ciphertext and the plaintext of one or more pieces of data. | | | A known plaintext attack is somewhat easier to mount than a chosen plaintext attack, because a known plaintext attack does not require the cryptanalyst to be able to feed data into the encryption device, it only requires him to know what data is being fed into the device. | | | Was our answer to What is a known plaintext attack? |
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http://www.tech-faq.com/known-plaintext-attack.shtml
(153 words)
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| | [No title] |
| | Removes single-character information, and forces attack to start at level of bigrams. | | | The program should not take long to write. | | | Suggests that encryption could be made robust against this attack by re-organizing the alphabet so that all common letters have even indices. |
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http://www.cs.rochester.edu/~nelson/courses/cryptology/notes/lecture_02.txt
(1211 words)
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| | Glossary Page 5 |
| | MIPS - Millions of Instructions Per Second, a measurement of computing speed. | | | Message Authentication Code (MAC) - A MAC is a function that takes a variable length input and a key to produce a fixed-length output. | | | meet-in-the-middle attack - A known plaintext attack against double encryption with two separated keys where the attacker encrypts a plaintext with a key and "decrypts" the original ciphertext with another key and hopes to get the same value. |
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http://www.lexias.com/html/glossary5.html
(519 words)
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| | [No title] |
| | (This type of codebreaking is called a "known-plaintext attack" on a cryptosystem. | | | For example, if every message starts with "Dear Bob,...", then Eve can immediately see (from the encoded message) which letters are used to encode the letters a, b, d, e and o. | | | The British used this kind of analysis during World War II to help figure out the key to the German Enigma cryptosystem, which was changed daily. |
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http://www.cs.yorku.ca/acm/Problems/2004-MAR-17/B.html
(411 words)
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| | [No title] |
| | At the moment, there is no known method to extract the password from the compressed file, so the only available methods are "brute force", dictionary-based and known-plaintext attacks. | | | Well, there are a lot of programs like this around, but all of them have their own "pros" and "cons". |
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http://www.elcomsoft.com/AZPR/readme.txt
(94 words)
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| | Murky.org: Known Plaintext Attack - Worked Example |
| | In the first position we find that a key of 'WOMBLEWO' is applied, or 'WOMBLE' repeating after six characters. | | | So an astute observer might have tried assuming that the plaintext contained 'BEAUFORT', and slid this along the message in order to try and work out what the key is. |
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http://murky.org/archives/2004/10/known_plaintext_1.html
(329 words)
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