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Topic: Preimage attack

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	Cryptography Research - Hash Collision Q&A
		A: A preimage attack would enable someone to find an input message that causes a hash function to produce a particular output.
		The attacks announced at CRYPTO 2004 are collision attacks, not preimage attacks.
		For example, a devastating attack would be one that enabled adversaries to obtain a legitimate server certificate with a collision to one containing a wildcard for the domain name and an expiration date far in the future.
	www.cryptography.com /cnews/hash.html (1054 words)

	SHA hash functions - the free encyclopedia (Site not responding. Last check: 2007-09-15)
		A collision attack also does not present the same kinds of risks that a preimage attack would.
		In attacking download verification, the attacker would have to construct a download — withthe attacker's trojan payload — that hadthe same checksum as the single "good" checksum; the unpublished result does not allow this.
		Constructing a password that worksfor a given account requires a preimage attack (and access to the shadow password file, which may or may not be trivial).
	www.world-knowledge-encyclopedia.com /?t=Sha (2106 words)

	Anxiety Attack Yolo (Site not responding. Last check: 2007-09-15)
		It offers readers practical exercises anxiety attack yolo and specific strategies for dealing with feelings, thoughts, anxiety attack yolo and physical symptoms associated with anxiety attacks, anxiety attack yolo and methods for strengthening social, sexual, anxiety attack yolo and interpersonal skills that can be the source of anxiety.
		In a preimage attack, the attacker starts with a particular output, and is able to find an input that will produce that particular output, whereas a collision attack merely finds two inputs that produce the same output.
		Bit-flipping attack - A bit-flipping attack is an attack on a cryptographic cipher in which the attacker can change the ciphertext in such as a way as to result in a predictable change of the plaintext, although the attacker is not able to learn the plaintext itself.
	yourhiddenfear.com /anxietyattackyolo.html (740 words)

	Anxiety Attack Orangevale (Site not responding. Last check: 2007-09-15)
		Chosen-ciphertext attack - A chosen-ciphertext attack (CCA) is an attack model for cryptanalysis in which the cryptanalyst chooses a ciphertext and causes it to be decrypted with an unknown key.
		Specific forms of this attack are sometimes termed "lunchtime" or "midnight" attacks, referring to a scenario in which an attacker gains access to an unattended decryption machine.
		Preimage attack - In cryptography, a preimage attack on a cryptographic hash differs from a collision attack.
	www.yourhiddenfear.com /anxietyattackorangevale.html (858 words)

	md5 - Article and Reference from OnPedia.com
		While this was not an attack on the full MD5 hash function, it was close enough for cryptographers to recommend switching to a replacement, such as WHIRLPOOL, SHA-1 or RIPEMD-160.
		Their analytical attack was reported to take only one hour on an IBM P690 cluster.
		They do not make it easy to perform a preimage attack, finding a message with a specified MD5 hash, or a second preimage attack, finding a message with the same MD5 hash as a given message.
	www.onpedia.com /encyclopedia/MD5 (1443 words)

	RFC 4270 (rfc4270) - Attacks on Cryptographic Hashes in Internet Protocols
		In a first-preimage attack, you know a hash value but not the message that created it, and you want to discover any message with the known hash value; in the second-preimage attack, you have a message and you want to find a second message that has the same hash.
		For this attack to work, the attacker needs to be able to predict the contents and structure of the certificate before it is issued, including the identity that will be used, the serial number that will be included in the certificate, and the start and stop dates of the validity period for the certificate.
		A preimaging attack that costs trillions of dollars and takes decades to preimage one desired hash value or one message is not practical; one that costs a few thousand dollars and takes a few weeks might be very practical.
	www.faqs.org /rfcs/rfc4270.html (3239 words)

	RFC 4270 (Site not responding. Last check: 2007-09-15)
		RFC 4270 Attacks on Hashes November 2005 length" and is often denoted as "L"; the result of applying the hash algorithm on a particular chunk of data is called the "hash value" for that data.
		RFC 4270 Attacks on Hashes November 2005 The collision attack on PKIX certificates described in early 2005 relied on the ability of the attacker to create two different public keys that would cause the body of the certificate to have the same hash value.
		A preimaging attack that costs trillions of dollars and takes decades to preimage one desired hash value or one message is not practical; one that costs a few thousand dollars and takes a few weeks might be very practical.
	www.armware.dk /RFC/rfc/rfc4270.html (3309 words)

	SWITCHmirror - Internet-Drafts & RFC
		In a first-preimage attack, you know a hash value but not the message that created it, and you want to discover any message with the known hash value; in the second-preimage attack, you have a message and you want to find a second message that has the same hash.
		For this attack to work, the attacker needs to be able to predict the contents and structure of the certificate before it is issued, including the identity that will be used, the serial number that will be included in the certificate, and the start and stop dates of the validity period for the certificate.
		The effective result of this attack is that one person using a single identity can get a digital certificate over one public key, but be able to pretend that it is over a different public key (but with the same identity, valid dates, and so on).
	mirror.switch.ch /cgi-bin/search/nph-findstd?preview=4270&scope=rfc (2433 words)

	[No title] (Site not responding. Last check: 2007-09-15)
		In a first-preimage attack, you know a hash value but not the message that created it, and you want to discover that message; in the second-preimage attack, you have a message and you want to find a second message that has the same hash.
		For this attack to work, the attacker needs to be able to predict the entire contents and structure of the certificate before it is issued, including the identity that will be used, the serial number that will be included in the certificate, and the start and stop dates of the validity period for the certificate.
		A preimaging attack that costs trillions Hoffman & Schneier Expires September 26, 2005 [Page 8] Internet-Draft Attacks on Hashes March 2005 of dollars and takes decades to preimage one desired hash value or one message is not practical; one that costs a few thousands of dollars and takes a few weeks might be very practical.
	faqs.org /ftp/pub/pub/internet-drafts/draft-hoffman-hash-attacks-00.txt (3175 words)

	seclog.de » Preimage Attacks on MD5 with the help of rainbow tables?
		A preimage attack on a cryptographic hash is an attempt to find a message that has a specific hash value.(picture: M is given, search M’ with same hash)
		A non arbitrary plaintext is searched during a preimage attack in order to have two different, desired plaintexts with the same corresponding hash.
		In the preimage attack, M and its hash value is given.
	seclog.de /2006/10/11/101 (879 words)

	[No title]
		In a first-preimage attack, you know a hash value but not the message that created it, and you want to discover that message; in the second-preimage attack, you have a message and you want to find a second message that has the same hash.
		For this attack to work, the attacker needs to be able to predict the entire contents and structure of the certificate before it is issued, including the identity that will be used, the serial number that will be included in the certificate, and the start and stop dates of the validity period for the certificate.
		A preimaging attack that costs trillions Hoffman & Schneier Expires September 26, 2005 [Page 8] Internet-Draft Attacks on Hashes March 2005 of dollars and takes decades to preimage one desired hash value or one message is not practical; one that costs a few thousands of dollars and takes a few weeks might be very practical.
	ietfreport.isoc.org /all-ids/draft-hoffman-hash-attacks-00.txt (3175 words)

	Gene6 FTP & Mail Server Forum > OTP S/Key SHA1
		On 17 August 2005, an improvement on the SHA-1 attack was announced on behalf of Xiaoyun Wang, Andrew Yao and Frances Yao at the CRYPTO 2005 rump session, lowering the complexity required for finding a collision in SHA-1 to 263.
		A collision attack does not present the same kinds of risks that a preimage attack would.
		Constructing a password that works for a given account requires a preimage attack (and access to the shadow password file, which may or may not be trivial).
	www.g6ftpserver.com /forum/lofiversion/index.php?t1844.html (731 words)

	[IMC-Tech] HASHING IS POINTLESS
		This attack, like the recently published attacks on MD5, is a _collision_ attack which doesn't affect the majority of security applications of cryptographic hashes (except perhaps some uses of digital signatures).
		A collision attack means that you have found a way to generate two different plaintexts (they don't even have to be meaningful) that hash to the same thing and that you can do it more efficiently than brute force (2 ^ (n / 2)).
		A much more difficult and dangerous attack that would break a lot of things would be discovering an efficient way to take the output of a hash function (a hash) and "reverse" it to generate a plaintext that will hash to the original value.
	lists.indymedia.org /pipermail/imc-tech/2005-June/0627-j9.html (249 words)

	MD2 - Encyclopedia, History, Geography and Biography
		Rogier and Chauvaud (1997) described collisions of MD2's compression function, although they were unable to extend the attack to the full MD2.
		In 2004, MD2 was shown to be vulnerable to a preimage attack with time complexity equivalent to 2
		Lars R. Knudsen and John Erik Mathiassen, Preimage and Collision Attacks on MD2.
	www.arikah.net /encyclopedia/MD2 (386 words)

	Preimage attack - Wikipedia, the free encyclopedia
		In cryptography, a preimage attack on a cryptographic hash is an attempt to find a message that has a specific hash value.
		First Preimage attack : given a hash h, find a message m such that hash(m) = h.
		A preimage attack differs from a collision attack in that there is a fixed hash or message that is being attacked.
	en.wikipedia.org /wiki/Preimage_attack (156 words)

	The Ultimate SHA hash functions Dog Breeds Information Guide and Reference
		In February 2005, Bruce Schneier reported an attack by Xiaoyun Wang, Yiqun Lisa Yin, and Hongbo Yu The attack is not yet published, but is outlined in a brief note by the authors.
		The details of the attack remain to be seen, but the authors write: "In particular, our analysis is built up on the original differential attack on SHA0, the near collision attack on SHA0, the multi-block collision techniques, as well as the message modification techniques used in the collision search attack on MD5.
		In attacking download verification, the attacker would have to construct a download — with the attacker's trojan payload — that had the same checksum as the single "good" checksum; the unpublished result does not allow this.
	www.dogluvers.com /dog_breeds/SHA (2165 words)

	SingaporeMoms - Parenting Encyclopedia - SHA hash functions
		In February 2005, Bruce Schneier reported an attack by Xiaoyun Wang, Yiqun Lisa Yin, and Hongbo Yu The attack is not yet published, but is outlined in a brief note by the authors.
		The details of the attack remain to be seen, but the authors write: "In particular, our analysis is built up on the original differential attack on SHA0, the near collision attack on SHA0, the multi-block collision techniques, as well as the message modification techniques used in the collision search attack on MD5.
		In attacking download verification, the attacker would have to construct a download — with the attacker's trojan payload — that had the same checksum as the single "good" checksum; the unpublished result does not allow this.
	www.singaporemoms.com /parenting/SHA (2153 words)

	MD5 - Biocrawler (Site not responding. Last check: 2007-09-15)
		In 1996, Dobbertin announced a collision of the compression function of MD5 (Dobbertin, 1996).
		If someone presents you with information such as a public key, its MD5 hash might not uniquely identify it: the other person might have a second public key with the same MD5 hash.
		Hans Dobbertin, The Status of MD5 After a Recent Attack, in CryptoBytes 2(2), 1996 [6] (http://www.rsasecurity.com/rsalabs/node.asp?id=2149).
	www.biocrawler.com /encyclopedia/MD5 (1525 words)

	RFC 4270
		The attacks against SHA-1 are not feasible with today's computers, but will be if the attacks are improved or Moore's Law continues to make computing power cheaper.
		The basic idea behind the collision attack on a hash algorithm used in a digital-signature protocol is that the attacker creates two messages that have the same hash value, causes one of them to be signed, and then uses that signature over the other message for some nefarious purpose.
		The collision attack on PKIX certificates described in early 2005 relied on the ability of the attacker to create two different public keys that would cause the body of the certificate to have the same hash value.
	www.apps.ietf.org /rfc/rfc4270.html (3255 words)

	LaQuSO General Security Attack Tree (Site not responding. Last check: 2007-09-15)
		Explanation: A type of cryptographic attack that assumes that the attacker has a given ciphertext and turns it into plaintext.
		In cryptography, a preimage attack on a cryptographic hash differs from a collision attack.
		In a preimage attack, the attacker starts with a particular output, and is able to find an input that will produce that particular output, whereas a collision attack merely finds two inputs that produce the same output.
	www.laquso.com /security/index.php?p=96 (105 words)

	How difficult is it to fool PROM verification of kernel code? - DealDatabase Forum - Deals, Freebies, and TiVo & ...
		You really need a preimage attack, not a collision attack so I'm not sure how relevant the result is anyway.
		In general a preimage attack refers to finding a second image of the same length as the original.
		If you could, that would be a major flaw in the algorithm and a preimage attack would be trivial.
	www.dealdatabase.com /forum/showthread.php?p=265986#post265986 (1316 words)

	DevNetwork Forums :: View topic - Checking for file alterations
		Just because they haven't found a full preimage attack doesn't change the fact that the hash is compromised in a substantial way - and in a way that is specifically important to the original poster.
		The paper you're referring to does not describe a preimage attack, and you again seem to be suggesting that it does.
		The pragmatic reason for moving away from MD5 (at least using it plainly, without the use of a salt or any similar technique), is that a preimage attack is imminent.
	forums.devnetwork.net /viewtopic.php?p=222967&... (3534 words)

	Upto11.net - Wikipedia Article for MD5
		While this was not an attack on the full MD5 hash function, it was close enough for cryptographers to recommend switching to a replacement, such as WHIRLPOOL, SHA-1 or RIPEMD-160.
		The size of the hash andmdash; 128 bits andmdash; is small enough to contemplate a brute force birthday attack.
		Their analytical attack was reported to take only one hour on an IBM P690 cluster.
	www.upto11.net /generic_wiki.php?q=md5 (1393 words)

	[17] - nsec3 - Trac
		Unsigned delegation point NS records can be deleted during a man in the middle attack, effectively denying existence of the delegation.
		A second attack vector exists in that an adversary is able to successfully fabricate a response claiming a not existent delegation to exist, though unsigned.
		The second-preimage resistance property means that it is computationally infeasible to find another message with the same hash value as a given message, i.e.andnbsp;given preimage X, to find a second preimage X' <> X such that hash(X) = hash(X').
	www.nsec3.org /cgi-bin/trac.cgi/changeset/17 (2568 words)

	Cryptanalysis: Collision attack in Hashing : Palisade
		In a preimage attack, an attacker tries to guess the input message from which a hash function produces a particular output.
		In a collision attack an attacker finds two messages with the same hashed output and sends the incorrect one to the receiver.
		According to the research carried out by these scientists collision attack on SHA-1 requires an estimated work factor of 2(power)69 (approximately 590 billion) hash computations and it is way beyond the capacity of a normal computer.
	palisade.plynt.com /issues/2005Jun/collision-attack (581 words)

	[No title]
		A second attack vector exists in that an adversary is able to successfully fabricate a response claiming a not existent delegation to exist, though unsigned.
		Note that the adversary can't mount this attack on an existing name but only on a name that the adversary can't choose and does not yet exist.
		This attack is prevented by changing the salt on a regular basis.
	www.watersprings.org /pub/id/draft-ietf-dnsext-nsec3-01.txt (4456 words)

	[No title] (Site not responding. Last check: 2007-09-15)
		Introduction In summer 2004, a team of researchers showed concrete evidence that the MD5 hash algorithm was susceptible to collision attacks [MD5- attack].
		Hoffman & Schneier Expires November 10, 2005 [Page 2] Internet-Draft Attacks on Hashes May 2005 o The attacks against SHA-1 are not feasible with today's computers, but will be if the attacks are improved or Moore's Law continues to make computing power cheaper.
		In other words, to thwart a hash collision attack in a non- repudiation protocol where a human is using a signed message as authorization, the signer needs to keep a copy of the original message they signed.
	www.faqs.org /ftp/pub/internet-drafts/draft-hoffman-hash-attacks-03.txt (3257 words)

	Educated Guesswork: Next steps for hash functions
		The point is, this attack can only be mounted by the one who created the message to be signed.
		Now, it looks like the Wang attack is using knowledge of the bits, but since they haven't published their techniques, it's hard to be sure.
		However, it seems to me that that's not the security environment in which a second preimage attack is likely to be useful.
	www.educatedguesswork.org /movabletype/archives/2005/02/next_steps_for_1.html (1806 words)

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