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Topic: Chosen plaintext attack


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In the News (Tue 21 May 19)

  
  What is a chosen plaintext attack?
A chosen plaintext attack is an attack where the cryptanalyst is able to define his own plaintext, feed it into the cipher, and analyze the resulting ciphertext.
Mounting a chosen plaintext attack requires the cryptanalyst to be able to send data of his choice into the device which is doing the encryption, and it requires the cryptanalyst to be able to view the output from the device.
Because of these requirements, a chosen plaintext attack is in some cases impossible to attempt.
www.tech-faq.com /chosen-plaintext-attack.shtml   (132 words)

  
  Chosen plaintext attack - Wikipedia, the free encyclopedia
A chosen plaintext attack is any form of cryptanalysis which presumes that the attacker has the capability to choose arbitrary plaintexts to be encrypted and obtain the corresponding ciphertexts.
Chosen plaintext attacks become extremely important in the context of public key cryptography, where the encryption key is public and the attacker can encrypt any ciphertext she chooses.
Conventional symmetric ciphers, in which the same key is used to encrypt and decrypt a text, may also be vulnerable to other forms of chosen plaintext attack, for example, differential cryptanalysis of block ciphers.
en.wikipedia.org /wiki/Chosen_plaintext_attack   (397 words)

  
 Known-plaintext attack - Wikipedia, the free encyclopedia
The known-plaintext attack is a cryptanalytic attack in which the attacker has samples of both the plaintext and its encrypted version (ciphertext) and is at liberty to make use of them to reveal further secret information; typically this is the secret key.
The known plaintexts were called "cribs", and schemes to force the Germans to produce them were called "gardening".
Encrypted file archives such as ZIP are also very prone to this attack.
en.wikipedia.org /wiki/Known-plaintext_attack   (204 words)

  
 Chosen plaintext attack - Wikipedia, the free encyclopedia
The attack would gain some further information, typically the secret key.
In addition, any cipher that can prevent chosen-plaintext attacks is then also guaranteed to be secure against known-plaintext and ciphertext-only attacks; this is a conservative approach to security.
Conventional symmetric ciphers, in which the same key is used to encrypt and decrypt a text, are often vulnerable to this type of attack, for example, differential cryptanalysis of block ciphers.
www.encyclopedia-online.info /Chosen-plaintext_attack   (256 words)

  
 Chosen plaintext attack   (Site not responding. Last check: 2007-10-26)
A chosen plaintext attack is any form of cryptanalysis which presumes that the attacker has the capability to choose arbitrary plaintext s to be encrypted and obtain the corresponding ciphertext s.
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www.serebella.com /encyclopedia/article-Chosen_plaintext_attack.html   (566 words)

  
 Lexias
A Cryptanalyst can mount an attack of this type in a scenario in which he or she has free use of a piece of decryption hardware, but is unable to extract the decryption key from it.
adaptive-chosen-plaintext - A special case of the chosen-plaintext attack in which the cryptanalyst is able to choose plaintexts dynamically, and alter his or her choices base on the results of previous encryptions.
See algebraic attack, birthday attack, brute force attack, chosen ciphertext attack, chosen plaintext attack, differential cryptanalysis, known plaintext attack, linear cryptanalysis, middleperson attack.
www.lexias.com /2.0/glossary1.html   (447 words)

  
 Hobnob   (Site not responding. Last check: 2007-10-26)
A special case of the chosen-plaintext attack in which the cryptanalyst is able to choose plaintexts dynamically, and alter his or her choices based on the results of previous encryptions.
An attack where the cryptanalyst may choose the ciphertext to be decrypted.
A chosen plaintext attack relying on the analysis of the evolution of the differences between two plaintexts.
www.hobnob.com /mcs225/glossary.html   (4248 words)

  
 Xref: info.physics.utoronto.ca news.answers:30458 sci.answers:1663 sci.crypt:30437 talk.an
Note that known-plaintext attacks are often defined in the literature as producing information about the key, but this is pointless: the cryptanalyst generally cares about the key only insofar as it lets him decrypt further messages.
A chosen-plaintext attack is the first of an increasingly impractical series of _active_ attacks on a cryptosystem: attacks where the cryptanalyst feeds data to the encryptor.
More absurd examples of this sort of attack are the ``chosen-key attack'' and ``chosen-system attack.'' A much more important form of active attack is a message corruption attack, where the attacker tries to change the ciphertext in such a way as to make a useful change in the plaintext.
www.skepticfiles.org /faq/crypto04.htm   (1180 words)

  
 [No title]   (Site not responding. Last check: 2007-10-26)
Substitution cipher: A map from characters in the plaintext to the ciphertext.
Ciphertext = plaintext XOR key Plaintext = key XOR ciphertext It turns out that as long as key is truly random, ciphertext is also random -- no frequency analysis possible.
Formally: Given a plaintext sequence b1.b2.....bn Where each bi is a fixed-length bit string and a key K ciphertext for bi: ci = Ek(bi) Ciphertext c for m = E(k,b0).E(k,b1).E(k.b2)....
www.eecs.umich.edu /~aprakash/eecs498/handouts/02-crypto-background.txt   (668 words)

  
 Chosen plaintext attack   (Site not responding. Last check: 2007-10-26)
A chosen plaintext attack is any form of cryptanalysis which presumes that the attacker has capability to choose arbitrary plaintexts to be encrypted and obtain the ciphertexts.
In addition any cipher that can chosen-plaintext attacks is then also guaranteed to secure against known-plaintext and ciphertext-only attacks; this is a approach to security.
Conventional symmetric ciphers in which the same key is to encrypt and decrypt a text are vulnerable to this type of attack for differential cryptanalysis of block ciphers.
www.freeglossary.com /Chosen_plaintext   (338 words)

  
 Articles - Cryptanalysis   (Site not responding. Last check: 2007-10-26)
In academia, new designs are regularly presented, and are also frequently broken: the 1984 block cipher Madryga was found to be susceptible to ciphertext-only attacks in 1998; FEAL-4, proposed as a replacement for the DES standard encryption algorithm, was demolished by a spate of attacks from the academic community, many of which are entirely practical.
A chosen-plaintext attack is less likely, but it is sometimes plausible: for example, you could convince someone to forward a message you have given them, but in encrypted form.
Related-key attacks are mostly theoretical, although they can be realistic in certain situations, for example, when constructing cryptographic hash functions using a block cipher.
www.gaple.com /articles/Cryptanalysis   (2326 words)

  
 Chosen plaintext attack   (Site not responding. Last check: 2007-10-26)
This appears, at first glance, to be an unrealistic model; it would certainly be unlikely that an attacker could to persuade ahuman cryptographer to encrypt large amounts of plaintexts of the attacker's choosing.
In addition, any cipher that can prevent chosen-plaintext attacks is then also guaranteed to be secureagainst known-plaintext and ciphertext-only attacks;this is a conservative approach to security.
Conventional symmetric ciphers, in which the samekey is used to encrypt and decrypt a text, are often vulnerable to this type of attack, for example, differential cryptanalysis of block ciphers.
www.therfcc.org /chosen-plaintext-attack-72518.html   (231 words)

  
 Table of Contents for Luby, M.: Pseudorandomness and Cryptographic Applications.   (Site not responding. Last check: 2007-10-26)
attack, and design of a stream private key cryptosystern that is secure against these attacks based on a pseudorandom generator.
Construction of a block private key cryptosystern secure against chosen plaintext attack based on a pseudorandom function generator.
Definition of a pseudorandom invertible permutation generator and discussion of applications to the construction of a block private key cryptosystern secure against chosen plaintext attack.
pup.princeton.edu /TOCs/oct04/c5154.html   (644 words)

  
 Attacks   (Site not responding. Last check: 2007-10-26)
The three basic attacks used for breaking a cryptographic scheme are known as ciphertext only, known plaintext and chosen plaintext.
In a ``chosen plaintext'' attack, the cryptanalyst can submit plaintext of his choice to encryption and gain access to the resulting ciphertext.
Algorithms which resist ciphertext only and known plaintext attacks might still be susceptible to chosen plaintext attacks.
www.maths.mq.edu.au /~steffen/old/PCry/report/node6.html   (228 words)

  
 Cryptanalysis of MultiSwap   (Site not responding. Last check: 2007-10-26)
However, the attack on DRM described by Beale Screamer would be much more practical, so we feel that these weaknesses in MultiSwap do not pose a significant threat to DRM at this time.
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.
Recall there are two stages to the attack: recover k5 and k11, and recover the rest of the key.
www.cs.berkeley.edu /~rtjohnso/multiswap   (1884 words)

  
 Q63: At What Point Does an Attack Become Practical?   (Site not responding. Last check: 2007-10-26)
A chosen plaintext or chosen ciphertext attack gives the cryptanalyst the greatest freedom in analyzing a cipher.
The cryptanalyst chooses the plaintext to be encrypted and analyzes the plaintext together with the resultant ciphertext to derive the secret key.
A known plaintext attack is more useful to the cryptanalyst than a chosen plaintext attack (with the same amount of data) since the cryptanalyst now requires a certain numbers of plaintexts and their corresponding ciphertexts without specifying the values of the plaintexts.
www.x5.net /faqs/crypto/q63.html   (361 words)

  
 N-057: Cryptographic weaknesses in Kerberos v4 protocol
None of the attacks discovered so far can be implemented given a KDC that accepts but does not issue 3DES tickets, so we believe that leaving this functionality in as compatibility for a version or two is reasonable.
You also need to be able to construct the first block of the ticket; you don't know what plaintext to use because the IV for the first block is the long-term service key.
This is sufficient to meet conditions of vulnerabilities (1) and (2) above and to encrypt arbitrary plaintext in the service keys of realm A and B. 5) Kerberos 4 Ticket Printing The conditions of (2) above are sufficient to print arbitrary tickets in a triple DES service key.
www.ciac.org /ciac/bulletins/n-057.shtml   (2962 words)

  
 Definition of Ciphertext-only attack
In cryptography, a ciphertext-only attack is a form of cryptanalysis where the attacker is assumed to have access only to a set of ciphertexts.
The attack is completely successful if the corresponding plaintexts can be deduced, or even better, the key.
A cipher whose key space is too small is subject to brute force attack with access to nothing but ciphertext by simply trying all possible keys.
www.wordiq.com /definition/Ciphertext-only_attack   (548 words)

  
 Read about Chosen plaintext attack at WorldVillage Encyclopedia. Research Chosen plaintext attack and learn about ...   (Site not responding. Last check: 2007-10-26)
cryptanalysis which presumes that the attacker has the capability to choose arbitrary plaintexts to be encrypted and obtain the corresponding
known-plaintext and ciphertext-only attacks; this is a conservative approach to security.
symmetric ciphers, in which the same key is used to encrypt and decrypt a text, are often vulnerable to this type of attack, for example,
encyclopedia.worldvillage.com /s/b/Chosen_plaintext_attack   (288 words)

  
 nCipher Security Resources: Glossary   (Site not responding. Last check: 2007-10-26)
A known plaintext attack that uses linear approximations to describe the behavior of the block cipher.
A known plaintext attack against double encryption with two separate keys where the attacker encrypts a plaintext with a key and ÒdecryptsÓ the original ciphertext with another key and hopes to get the same value.
A property of a stream cipher, stating that the keystream is generated independently of the plaintext and ciphertext.
www.ncipher.com /resources/downloads/sr_glossary.php   (4724 words)

  
 94111505.HTM   (Site not responding. Last check: 2007-10-26)
Known or chosen plaintext attacks can use this effect, but, in : the general case, it won't do anything to simplify the analysis.
An unknown plaintext attack is to consider short pieces, say 8 to 24 bits long, of the ciphertext.
If the redundancy of both plaintexts is typical, that is, much over 50%, and the attacker's model captures the bulk of the redundancy, this should work.
www.ciphersbyritter.com /NEWS2/94111505.HTM   (276 words)

  
 [No title]
As a thought experiment, suppose B is very resistant to known plaintext attacks, but succumbs easily to a chosen plaintext attack.
Let S be a set of plaintexts which are useful in a chosen plaintext attack.
The disadvantage is that this method expands the length of the plaintext by a factor of two.
www.eecs.berkeley.edu /~daw/my-posts/combine   (825 words)

  
 Vulnerability of SSL to Chosen-Plaintext Attack - Bard (ResearchIndex)
When utilizing block ciphers for encryption, the SSL standard mandates the use of the cipher block chaining (CBC) mode of encryption which requires an initialization vector (IV) in order to encrypt.
Although the initial IV used by SSL is a (pseudo)random string which is generated and shared during the initial handshake phase, subsequent IVs used by SSL are chosen in a deterministic,...
Algebraic Attacks on Combiners with Memory and Several Outputs - Courtois (2003)
citeseer.ist.psu.edu /bard04vulnerability.html   (405 words)

  
 Known plaintext attack   (Site not responding. Last check: 2007-10-26)
The known-plaintext attack is a cryptanalytic attackin which the attacker has samples of both the plaintext and its encrypted version (ciphertext) and isat liberty to make use of them to reveal further secret information; typically this is the secret key.
At Bletchley Park in World War II, strenuous efforts were made to use, and even force the Germans to produce messages with, knownplaintext.
The known plaintexts were called " cribs ", and schemes to force the Germans toproduce them were called " gardening ".
www.therfcc.org /known-plaintext-attack-72516.html   (101 words)

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