Collisions for the compression function of MD5
02 Jan 1994-pp 293-304
TL;DR: In this paper an algorithm is described that finds collisions for the compression function of MD5 and results in an approximate relation between any four consecutive additive constants.
Abstract: At Crypto '91 Ronald L. Rivest introduced the MD5 Message Digest Algorithm as a strengthened version of MD4, differing from it on six points. Four changes are due to the two existing attacks on the two round versions of MD4. The other two changes should additionally strengthen MD5. However both these changes cannot be described as well-considered. One of them results in an approximate relation between any four consecutive additive constants. The other allows to create collisions for the compression function of MD5. In this paper an algorithm is described that finds such collisions.A C program implementing the algorithm establishes a work load of finding about 216 collisions for the first two rounds of the MD5 compression function to find a collision for the entire four round function. On a 33MHz 80386 based PC the mean run time of this program is about 4 minutes.
Citations
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IBM1
TL;DR: It is argued that the random oracles model—where all parties have access to a public random oracle—provides a bridge between cryptographic theory and cryptographic practice, and yields protocols much more efficient than standard ones while retaining many of the advantages of provable security.
Abstract: We argue that the random oracle model—where all parties have access to a public random oracle—provides a bridge between cryptographic theory and cryptographic practice. In the paradigm we suggest, a practical protocol P is produced by first devising and proving correct a protocol PR for the random oracle model, and then replacing oracle accesses by the computation of an “appropriately chosen” function h. This paradigm yields protocols much more efficient than standard ones while retaining many of the advantages of provable security. We illustrate these gains for problems including encryption, signatures, and zero-knowledge proofs.
5,313 citations
Cites background from "Collisions for the compression func..."
...This too does not make a suitable replacement for a random oracle, as [8] has demonstrated that collisions can be efficiently found in this map....
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22 May 2005
TL;DR: A new powerful attack on MD5 is presented, which unlike most differential attacks, does not use the exclusive-or as a measure of difference, but instead uses modular integer subtraction as the measure.
Abstract: MD5 is one of the most widely used cryptographic hash functions nowadays. It was designed in 1992 as an improvement of MD4, and its security was widely studied since then by several authors. The best known result so far was a semi free-start collision, in which the initial value of the hash function is replaced by a non-standard value, which is the result of the attack. In this paper we present a new powerful attack on MD5 which allows us to find collisions efficiently. We used this attack to find collisions of MD5 in about 15 minutes up to an hour computation time. The attack is a differential attack, which unlike most differential attacks, does not use the exclusive-or as a measure of difference, but instead uses modular integer subtraction as the measure. We call this kind of differential a modular differential. An application of this attack to MD4 can find a collision in less than a fraction of a second. This attack is also applicable to other hash functions, such as RIPEMD and HAVAL.
1,583 citations
Cites background from "Collisions for the compression func..."
...∆c 2 [−24,−25,−26, 27] + (∆φ7[3] ≪ 22) = 2 − 2 = −223....
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...Bosselaers [3] found a kind of pseudo-collision for MD5 which consists of the same message with two different sets of initial values....
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IBM1
TL;DR: A computational technique for combatting junk mail in particular and controlling access to a shared resource in general is presented, which requires a user to compute a moderately hard, but not intractable, function in order to gain access to the resource, thus preventing frivolous use.
Abstract: We present a computational technique for combatting junk mail in particular and controlling access to a shared resource in general. The main idea is to require a user to compute a moderately hard, but not intractable, function in order to gain access to the resource, thus preventing frivolous use. To this end we suggest several pricing Junctions, based on, respectively, extracting square roots modulo a prime, the Fiat-Shamir signature scheme, and the Ong-Schnorr-Shamir (cracked) signature scheme.
1,416 citations
Cites background from "Collisions for the compression func..."
...Also, [4] finds “pseudocollisions” in MD5, but it is not clear whether this can be converted into a collision finding algorithm....
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21 Feb 1996
TL;DR: A new version of RIPEMD with a 160-bit result is proposed, as well as a plug-in substitute for RIPEMd with a 128- bit result, and the software performance of several MD4-based algorithms is compared.
Abstract: Cryptographic hash functions are an important tool in cryptography for applications such as digital fingerprinting of messages, message authentication, and key derivation. During the last five years, several fast software hash functions have been proposed; most of them are based on the design principles of Ron Rivest's MD4. One such proposal was RIPEMD, which was developed in the framework of the EU project RIPE (Race Integrity Primitives Evaluation). Because of recent progress in the cryptanalysis of these hash functions, we propose a new version of RIPEMD with a 160-bit result, as well as a plug-in substitute for RIPEMD with a 128-bit result. We also compare the software performance of several MD4-based algorithms, which is of independent interest.
519 citations
22 May 2005
TL;DR: In this article, a chosen-message pre-image attack on MD4 with complexity below 28 was presented, where the complexity is only a single MD4 computation and a random message is a weak message with probability 2−2 to 2−6.
Abstract: MD4 is a hash function developed by Rivest in 1990 It serves as the basis for most of the dedicated hash functions such as MD5, SHAx, RIPEMD, and HAVAL In 1996, Dobbertin showed how to find collisions of MD4 with complexity equivalent to 220 MD4 hash computations In this paper, we present a new attack on MD4 which can find a collision with probability 2−2 to 2−6, and the complexity of finding a collision doesn't exceed 28 MD4 hash operations Built upon the collision search attack, we present a chosen-message pre-image attack on MD4 with complexity below 28 Furthermore, we show that for a weak message, we can find another message that produces the same hash value The complexity is only a single MD4 computation, and a random message is a weak message with probability 2−122
The attack on MD4 can be directly applied to RIPEMD which has two parallel copies of MD4, and the complexity of finding a collision is about 218 RIPEMD hash operations
501 citations
References
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Proceedings Article•
01 Apr 1992
TL;DR: This document describes the MD5 message-digest algorithm, which takes as input a message of arbitrary length and produces as output a 128-bit "fingerprint" or "message digest" of the input.
Abstract: This document describes the MD5 message-digest algorithm. The
algorithm takes as input a message of arbitrary length and produces as
output a 128-bit "fingerprint" or "message digest" of the input. This
memo provides information for the Internet community. It does not
specify an Internet standard.
3,514 citations
11 Aug 1990
TL;DR: The MD4 message digest algorithm takes an input message of arbitrary length and produces an output 128-bit "fingerprint" or "message digest", in such a way that it is (hopefully) computationally infeasible to produce two messages having the same message digest, or to produce any message having a given prespecified target message digest.
Abstract: The MD4 message digest algorithm takes an input message of arbitrary length and produces an output 128-bit "fingerprint" or "message digest", in such a way that it is (hopefully) computationally infeasible to produce two messages having the same message digest, or to produce any message having a given prespecified target message digest. The MD4 algorithm is thus ideal for digital signature applications: a large file can be securely "compressed" with MD4 before being signed with (say) the RSA public-key cryptosystem.The MD4 algorithm is designed to be quite fast on 32-bit machines. For example, on a SUN Sparc station, MD4 runs at 1,450,000 bytes/second (11.6 Mbit/sec). In addition, the MD4 algorithm does not require any large substitution tables; the algorithm can be coded quite compactly.The MD4 algorithm is being placed in the public domain for review and possible adoption as a standard.
550 citations
01 Sep 1991
TL;DR: Sometimes what the authors also need is collision resistance: it is hard to find two random messages M and M1 such that H(M)=H(M1) this is called birthday attack and is based on a birthday paradox.
Abstract: Sometimes what we also need is collision resistance: it is hard to find two random messages M and M1 such that H(M)=H(M1) This is called birthday attack and is based on a birthday paradox How many people must be in a room until the probability is greater than 0.5 that two of them have the same birthday? 23 For a hash function that produces m bit hash, it takes 2m/2 trials to find two messages that hash to the same value We need large m, currently 128-160
301 citations
11 Aug 1991
TL;DR: It is shown that if the three round MD4 algorithm is stripped of its first round, it is possible to find for a given (initial) input value two different messages hashing to the same output.
Abstract: In [Rive90] the MD4 message digest algorithm was introduced taking an input message of arbitrary length and producing an output 128-bit message digest. It is conjectured that it is computationally infeasible to produce two messages having the same message digest, or to produce any message having a given prespecified target message. In this paper it is shown that if the three round MD4 algorithm is stripped of its first round, it is possible to find for a given (initial) input value two different messages hashing to the same output. A computer program implementing this attack takes about 1 millisecond on a 16 Mhz IBM PS/2 to find such a collision.
105 citations