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In recent years, considerable effort has been devoted to research on hash function. Nevertheless, it’s hard to obtain the proporties of sensitivity, confusion and diffusion, collision resistance, and high efficiency simultaneously. Based on research of all attacks to classical hash functions, we propose a parallel and collision resistance hash function. With regard to the design of compression function, in order to resist attacks, such as birthday attack, forgery attack and multi-collision attack, we change the initial value of the chaining variable, which is processed through three-round iterations. On the aspect of iterative structure, instead of calculating sequentially, a parallel structure is designed. The improvement lies in the combination of two message blocks independently in each round. The statistical data and experimental analysis prove that the designed hash function algorithm has good properties of confusion and diffusion, collision resistance and superior efficiency, which can make it become a new type of candidate for hash function.

Preneel-Govaerts-Vandewalle (PGV) hash function schemes is a single-block-length hash function based on block cipher introduced by Preneel et al. in 1993. They proposed 64 basic ways to construct a (collision-resistant) hash functions from a block cipher. They regarded 12 of these 64 schemes are secure, though no proofs or formal claims were given. We take 4 schemes from those 12 schemes to analyzed. In this paper, we show different approach to find collisions in four secure PGV hash function schemes. The use of block cipher that has iterative differential such as PRESENT can let us to find collisions. In 2007, Wang found four iterative characteristics for 4-round PRESENT-80. Based on the analysis, we indicate that those four secure PGV schemes based on 4-round PRESENT-80 are not fulfilled collision resistance property.

To examine the integrity and authenticity of an IP address efficiently and economically, this paper proposes a new non-iterative hash function called JUNA that is based on a multivariate permutation problem and an anomalous subset product problem to which no subexponential time solutions are found so far. JUNA includes an initialization algorithm and a compression algorithm, and converts a short message of n bits which is regarded as only one block into a digest of m bits, where 80 ≤ m ≤ 232 and 80 ≤ m ≤ n ≤ 4096 . The analysis and proof show that the new hash is one-way, weakly collision-free, and strongly collision-free, and its security against existent attacks such as birthday attack and meet-in-the-middle attack is to O ( 2 m ) . Moreover, a detailed proof that the new hash function is resistant to the birthday attack is given. Compared with the Chaum–Heijst–Pfitzmann hash based on a discrete logarithm problem, the new hash is lightweight, and thus it opens a door to convenience for utilization of lightweight digital signing schemes.

Since the traditional classic hash function structure (MD structure) is suffering from all kinds of attacks, the research of new hash function structure becomes hot issue. This paper analyses these attacks, based on MD structure, this paper brings in two security parameters and improves the message padding scheme, and then designs a Double-Serial iterative structure. In this structure, since there are more message blocks affecting the chaining variables, it can not only avoid the traditional second collision attack, multicollision attack and second preimage attack of long message, but also accelerate the message diffusion and enhance the avalanche effect. According to the efficiency analysis and security authentication, this proposed structure improves security and has the same efficiency of Double-Pipe structure.

In this paper, we study the security of the LSH hash functions. We find that the wide-pipe MD-structural LSH hash functions apply the 17th PGV scheme which is "backward attackable". This property equips us with trivial attacks including pseudo-preimage, free-start collision, and Type II boomerang. These attacks can never be available to previous MD-structural hash functions like Skein. We stress that such trivial attacks can only be regarded as distinguishers rather than real threat to the LSH in nowadays' practical applications. But we should still be cautious about the possible malicious use of LSH in specific situations in the future. We also launch 14-round boomerang attacks on LSH-512 and LSH-256 hash functions with complexities 2308 and 2242, respectively. We verify the correctness of our boomerang attacks by giving practical 11-round boomerang quartets. To the best of our knowledge, these are the first practically verifiable boomerang results on the LSH hash functions. These boomerang results indicate that the round functions of LSH are well designed. Copyright © 2016 John Wiley & Sons, Ltd.

Hash functions have been used to address security requirements such as integrity, message authentication and non-repudiation. In WSNs, these functions are also used to preserve sensor nodes' identity (ID) anonymity, i.e., they are used to generate and verify dynamic pseudonyms that are used to identify sensor nodes in a communication session. In this latter application, there is an open issue as to how long the output of a hash function (i.e. hash value) we should use in pseudonym generation. The longer the hash value, the longer is the pseudonym, thus the harder it is to guess a pseudonym that is generated by using a hash function. On the other hand, the use of a longer hash value also means that the bandwidth and energy costs in transmitting the pseudonym will be higher. As sensor nodes typically have limited resources and are battery powered, the balance between the protection level of ID anonymity and performance and energy costs incurred in providing such a protection is an open issue. This paper inves- tigates the use of hash value truncation in preserving ID anonymity in WSNs and the impact of hash value truncation on four criteria attributes (security against brute force attacks, probability of pseudonym collisions, energy trade- off and end-to-end packet delivery delay). It reports the possible impacts of other factors including the type and usage of hash functions, sensor node capabilities, adversary capabilities, ability to resolve pseudonym collisions, network density and data collection rate. The results show that the impacts of these factors may be contradictory. Therefore, the determination of an optimal level of hash value truncation should consider all trade-offs brought by these factors.

Hash functions play important role in the information security era. Although there are different methods to design these functions, in recent years chaos theory has emerged as a strong solution in this area. Chaotic hash functions use one-dimensional maps such as logistic and tent, or employ complex multi-dimensional maps which are typically insecure or slow and most of them has been successfully attacked. In this paper, we propose a new chaotic system and employ it to design a secure and fast hash function. The improved security factor has roots in the hyper sensitivity of the proposed chaotic map while properties like speed and security can be parameterized. On the other hand, the proposed hash function has a dynamic random array of functions and can be implemented by a parallel architecture. This data-level parallel architecture makes it fast to generate the hash value. Statistical simulations show success of the proposed hashing scheme. Cryptanalysis of proposed function, such as key sensitivity, meet-in-the-middle attack, collision, preimage resistance and high level attacks, proves security of the proposed function.

We analyze the computational collision problem on a hash algorithm based on chaotic tent map, and then present an improvement of the original algorithm in this paper. More specifically, we utilize message extension to enhance the correlation of plaintexts in the message and aggregation operation to improve the correlation of sequences of message blocks, which significantly increase the sensitivity between message and hash values, thereby greatly resisting the collision. Finally, we evaluate the performance of the improved algorithm by computer simulation, and the results show that it can resist the computational collision and can satisfy the requirements of a more secure hash algorithm.

The safety application in vehicular ad hoc network provides active road safety to avoid road accidents by disseminating life critical information among drivers securely. Such information must be protected from the access of intruder or attacker. A timestamp defined hash algorithm is proposed in the present work for secure data dissemination among vehicles. The sender vehicle sends a deformed version of the original message along with the incomplete message digest to its neighbors. The receiver vehicle generates message digest from the deformed version of the original message and also from the incomplete message digest. It accepts the message if both the digests are equal. The proposed algorithm fulfils all the basic properties such as preimage resistance, collision resistance of a one-way unkeyed hash function. Finally the comparative usability of the hash algorithm in the said application domain is worked out and that shows the dominance of the scheme over the existing schemes.

RIPEMD-128 is an ISO/IEC standard cryptographic hash function proposed in 1996 by Dobbertin, Bosselaers and Preneel. The compression function of RIPEMD-128 consists of two different and almost independent parallel lines denoted by line1 operation and line2 operation. The initial values and the output values of the last step of the two operations are combined, resulting in the final value of one iteration. In this study, the authors present collision differential characteristics for both 40-step line1 operation and 40-step line2 operation by choosing a proper message difference. By using message modification technique, they improve the probabilities of the differential characteristics so that they can give a collision attack on 40-step RIPEMD-128 hash function with a complexity of 235 computations. Meanwhile, they improve the distinguishing attack proposed by Landelle and Peyrin at EUROCRYPT 2013, and give a distinguisher on the full RIPEMD-128 hash function with a complexity of 290.4 by doing message modification.

In August 2012, the Streebog hash function was selected as the new Russian cryptographic hash standard (GOST R 34.11-2012). In this study, the authors investigate the new standard in the context of malicious hashing and present a practical collision for a malicious version of the full hash function. In particular, they apply the rebound attack to find three solutions for three different differential paths for four rounds. Then, using the freedom of the round constants they connect them to obtain a collision for the 12 rounds of the compression function. Additionally, and because of the simple processing of the counter, they bypass the barrier of the checksum finalisation step and transfer the compression function collision to the hash function output with no additional cost. The presented attack has a practical complexity and is verified by an example. Although the results of this study may not have a direct impact on the security of the current Streebog hash function, it presents an urge for the designers to publish the origin of the used parameters and the rational behind their choices in order for this function to gain enough confidence and widespread adoption by the security community.

In this article we propose a new cryptanalysis method for double-branch hash functions and we apply it on the standard RIPEMD-128, greatly improving over previously known results on this algorithm. Namely, we are able to build a very good differential path by placing one nonlinear differential part in each computation branch of the RIPEMD-128 compression function, but not necessarily in the early steps. In order to handle the low differential probability induced by the nonlinear part located in later steps, we propose a new method for using the available freedom degrees, by attacking each branch separately and then merging them with free message blocks. Overall, we present the first collision attack on the full RIPEMD-128 compression function as well as the first distinguisher on the full RIPEMD-128 hash function. Experiments on reduced number of rounds were conducted, confirming our reasoning and complexity analysis. Our results show that 16-year-old RIPEMD-128, one of the last unbroken primitives belonging to the MD-SHA family, might not be as secure as originally thought.

main purpose of Message Authentication is to prevent manipulation of the message which is sent. MAC stands for Message Authentication Code which is also known as "Integrity Check Value" or "Cryptographic Checksum". The basic objectives of a hash function are to: • Prevent finding a message from a given hash value (Inversion) • Prevent finding two messages with the same hash value (Collision) On the other hand, Message Authentication Codes are mainly to prevent forgery. Thus, using hash functions for Message Authentication may get a bit complex as hash functions do not have the in-built functionality of a key. In this paper, we discuss a few popular cryptographic hashing algorithms and compare their performance with respect to each other. KeywordsAlgorithms, Authentication Code, MD5

HaF is a family of hash functions developed in Poland at Poznán University of Technology, see [1, 2]. It is a classical Merkle-Damgård construction with the output sizes of 256, 512 or 1024 bits. In this paper we present a collision attack with negligible complexity (collisions can be found without using a computer) for all the members of HaF family. We have also shown that the improved function (without the critical transformation) is still insecure. It is possible to find a preimage for a short message with the complexity lower than the exhaustive search. We are also able to create some fixed points with a complexity of single compression function call.

Hash functions play an important role in constructing cryptographic schemes that provide security services, such as confidentiality in an encryption scheme, authenticity in an authentication protocol and integrity in a digital signature scheme and so on. Such hash function is needed to process a challenge, a message, an identifier or a private key. In this paper, we propose an attack against HAVAL-3 hash function, which is used in open source Tripwire and is included in GNU Crypto. Under the meet-in-the-middle (MITM) preimage attack framework proposed by Aoki and Sasaki in 2008, the one-wayness of several (reduced-)hash functions had been broken recently. However, most of the attacks are of complexity close to brute-force search. Focusing on reducing the time complexity of such MITM attacks, we improve the preimage attacks against HAVAL-3 hash function to within lower time complexity and memory requirement, compared with the best known attack proposed by Sasaki and Aoki in ASIACRYPT 2008. Besides the 256-bit variant of HAVAL-3, similar improvements can be applied to some truncated variants as well. Interestingly, due to the low complexity of our attack, the preimage attack applies to the 192-bit variant of HAVAL-3 for the first time.

In this paper, we have proposed a new and an efficient cryptographic hash function based on random Latin squares generated through padding, shift operations and non-linear transformations. The developed hash scheme satisfies basic as well as desirable properties of an ideal hash function. Generation of Latin Squares for each plain text block strengthens the hash function. Removal of Duplicates and random padding have been implemented to achieve confusion and diffusion. Use of repeated lookups on Latin squares, non-linear transformations and complex shift operations further increase the strength of our cryptographic hash function at a low computational overhead and ensures that the hashing algorithm satisfy the principal properties of pre-image resistance and collision resistance.

The MD transform that underlies the MD and SHA families iterates a compression function h to get a hash function H. The question we ask is, what property X of h guarantees collision resistance (CR) of H? The classical answer is that X itself be CR. We show that weaker conditions X, in particular forms of what we call constrained-CR, suffice. This reduces demands on compression functions, to the benefit of security, and also, forensically, explains why collision-finding attacks on compression functions have not, historically, lead to immediate breaks of the corresponding hash functions. We obtain our results via a definitional framework called RS security, and a parameterized treatment of MD, that also serve to unify prior work and variants of the transform.

In cryptography, a hash function is a very important cryptographic primitive with a wide range of applications. There are three required properties for a good hash function, i.e., collision, pre-image, and second pre-image resistance. In this paper, we try to contest these properties on a popular and widely used hash function called MD5 - and its two simplified versions that we made. The birthday attack technique was used to test MD5's general collision resistance, while the brute force method was used in the search for pre-image and second pre-image collisions. We calculated the Hamming distance to monitor the progress in our search for a collision; the smaller the Hamming distance the better. Our input domain for the MD5 hash function consisted of hexadecimal bit-strings and strategically generated ASCII character strings. Since finding hash collisions demands much more computing power and storage, we wrote C parallel programs in conjunction with the Message Passing Interface (MPI) library that runs over multiple processors / cores in the heavily used CUNY HPC cluster called Penzias. Multiple search / sort / merge algorithms were tested, not only to reduce time and space complexities, but also to improve performance. Hash distributions, numerous arbitrary meaningless and a few meaningful collisions were found.

A hash function hashes a longer message of arbitrary length into a much shorter bit string of fixed length, called a hash. Inevitably, there will be a lot of different messages being hashed to the same or similar hash. We call this a hash collision or a partial hash collision. By utilizing multiple processors from the CUNY High Performance Computing Center's clusters, we can locate partial collisions for the hash functions MD5 and SHA1 by brute force parallel programming in C with MPI library. The brute force method of finding a second preimage collision entails systematically computing all of the permutations, hashes, and Hamming distances of the target preimage. We explore varying size target strings and the number of processors allocation to examine the effect these variables have on finding partial collisions. The results show that for the same message space the search time for the partial collisions is roughly halved for each doubling of the number of processors; the longer the message is the better partial collisions are produced.

The chaotic maps posses high parameter sensitivity, random-like behavior and one-way computations, which favor the construction of cryptographic hash functions. In this paper, we propose to present a novel hash function scheme which uses multiple chaotic maps to generate efficient variable-sized hash functions. The message is divided into four parts, each part is processed by a different 1D chaotic map unit yielding intermediate hash code. The four codes are concatenated to two blocks, then each block is processed through 2D chaotic map unit separately. The final hash value is generated by combining the two partial hash codes. The simulation analyses such as distribution of hashes, statistical properties of confusion and diffusion, message and key sensitivity, collision resistance and flexibility are performed. The results reveal that the proposed anticipated hash scheme is simple, efficient and holds comparable capabilities when compared with some recent chaos-based hash algorithms.

Designing a cryptographic scheme with minimal components is a main theme in cryptographic research. Regarding double-block-length (DBL) hashing, feed-forward operations are used to avoid attacks from the blockcipher’s decryption function, whereas Ozen and Stam showed that by using an iterated structure the feed-forward operations can be eliminated. Precisely, DBL iterated hash functions are collision resistant up to about \(2^n\) query complexity when a blockcipher with n-bit blocks is used.

Simpira v1 is a recently proposed family of permutations, based on the AES round function. The design includes recommendations for using the Simpira permutations in block ciphers, hash functions, or authenticated ciphers. The designers' security analysis is based on computer-aided bounds for the minimum number of active S-boxes. We show that the underlying assumptions of independence, and thus the derived bounds, are incorrect. For family member Simpira-4, we provide di erential trails with only 40 (instead of 75) active S-boxes for the recommended 15 rounds. Based on these trails, we propose full-round collision attacks on the proposed Simpira-4 Davies-Meyer hash construction, with complexity 282.62 for the recommended full 15 rounds and a truncated 256-bit hash value, and complexity 2110.16 for 16 rounds and the full 512-bit hash value. These attacks violate the designers' security claims that there are no structural distinguishers with complexity below 2128.

In this paper we attack a 2n-bit double length hash function proposed by Lee et al. This proposal is a blockcipher-based hash function with hash rate 2/3. The designers claimed that it could achieve ideal collision resistance and gave a security proof. However, we find a collision attack with complexity of O(23n/4) and a preimage attack with complexity of O(2 n ). Our result shows this construction is much worse than an ideal 2n-bit hash function.

A hash functionhMISRthat suitable for passive devices is proposed. Taking parallel LFSR as the basic componenthMISRprovides the security through one-wayness brought by the information loss in the process of compression. When implemented, the hardware complexity ofhMISRis much lower than Toeplitz hash.

Cryptographic hash functions are important cryptographic techniques and are used widely in many cryptographic applications and protocols. All the MD4 design based hash functions such as MD5, SHA-1, RIPEMD-160 and FORK-256 are built on Merkle-Damgård iterative method. Recent differential and generic attacks against these popular hash functions have shown weaknesses of both specific hash functions and their underlying Merkle-Damgård construction. In this paper we propose a hash function follows design principle of NewFORK-256 and based on HAIFA construction. Its compression function takes three inputs and generates a single output of 256-bit length. An extra input to a compression function is a 64-bit counter (number of bits hashed so far). HAIFA construction shows strong resistance against major generic and other cryptanalytic attacks. The security of proposed hash function against generic attacks, differential attack, birthday attack and statistical attack was analyzed in detail. It is shown that the proposed hash function has high sensitivity to an input message and is secure against different cryptanalytic attacks.

We present new techniques for the cryptanalysis of hash functions. Our contributions are two-fold: both on the search level of the compression function and on the meta-structure. The former led to the neutral bits technique, while the latter led to the multi-block technique. The usefulness of these techniques is demonstrated on SHA-0 and SHA-1, but they are applicable to other hash functions as well. We use these techniques to find a collision of the full SHA-0 which is the first published collision of this function, and very efficient collision attacks on reduced versions of SHA-1.

Hash functions have been among the most scrutinized cryptographic primitives in the previous decade, mainly due to the cryptanalysis breakthroughs on MD-SHAfamily and the NIST SHA-3 competition that followed. Grindahl is a hash function proposed at FSE 2007 that inspired several SHA-3 candidates. One of its particularities is that it follows the AES design strategy, with an efficiency comparable to SHA-256. This paper provides the first cryptanalytic work on this scheme and we show that the $$256$$256-bit version of Grindahl is not collision resistant. Our attack uses byte-level truncated differentials and leverages a counterintuitive method (reaching an internal state where all bytes are active) in order to ease the construction of good differential paths. Then, by a careful utilization of the freedom degrees inserted every round, and with a work effort of approximatively $$2^{112}$$2112 hash computations, an attacker can generate a collision for the full $$256$$256-bit version of Grindahl.

Non-cryptographic hash functions have been investigated to identify their pseudo-random nature when employed in the implementation of hash tables for real-time storage and look-up of uniform resource locators. Statistical studies have been performed on the sequences generated using five widely used non-cryptographic hash functions: (1) CRC, (2) Adler, (3) DJBX33A, (4) FNV, and (5) Murmur. The comparative analysis of tested non-cryptographic hash functions shows that the Adler hash function is not suitable for hash table implementation, whereas, the rest of non-cryptographic hash functions exhibit similar and better randomizing features which make them an attractive choice for hash table implementation.

Cryptographic hash functions are used to protect the authenticity of information. Some of the most popular and commonly used cryptographic hash algorithms are MD5, SHA1, RIPEMD. These hash algorithms are used in a wide variety of security applications e.g. securing node/message in traditional networks. However, the commonly used hash algorithms require huge computational overhead which is not affordable by applications in energy-starved network e.g. wireless sensor network (WSN). In these applications the major constraints are communication, computation and storage overheads; out of which communication and computation overheads consume high energy. Keeping this fact in mind, in this paper, a light-weight, one-way, cryptographic hash algorithm is developed with a target to produce a hash-digest with fixed and relatively small length for such an energy-starved wireless network. The primary focus is making the algorithm light-weight so that upon using it in application of network like WSN, the nodes can successfully run the algorithm with low energy. We claim the algorithm fulfils all the basic properties such as preimage resistance, collision resistance of a one-way unkeyed hash function. Finally the comparative usability of the hash algorithm in the said application domain is worked out and that shows the dominance of our scheme over two of the state-of-the-art hashing schemes.

Cryptographic hash functions are used to protect the integrity of information. Hash functions are designed by using existing block ciphers as compression functions. This is due to challenges and difficulties that are encountered in constructing new hash functions from the scratch. However, the key generations for encryption process result to huge computational cost which affects the efficiency of the hash function. This paper proposes a new, secure and efficient compression function based on a pseudorandom function, that takes in two 2n-bits inputs and produce one n-bit output (2n-to-n bit). In addition, a new keyed hash function with three variants is proposed (PinTar 128 bits, 256 bits and 512 bits) which uses the proposed compression as its underlying building block. Statistical analysis shows that the compression function is an efficient one way random function. Similarly, statistical analysis of the keyed hash function shows that the proposed keyed function has strong avalanche property and is resistant to key exhaustive search attack. The proposed key hash function can be used as candidate for developing security systems.

We introduce the rebound attack as a variant of differential cryptanalysis on hash functions and apply it to the hash function Whirlpool, standardized by ISO/IEC. We give attacks on reduced variants of the 10-round Whirlpool hash function and compression function. Our results are collisions for 5.5 and near-collisions for 7.5 rounds on the hash function, as well as semi-free-start collisions for 7.5 and semi-free-start near-collisions for 9.5 rounds on the compression function. Additionally, we introduce the subspace problem as a generalization of near-collision resistance. Finally, we present the first distinguishers that apply to the full compression function and the full underlying block cipher W of Whirlpool.

In this paper, the relationships between perfect nonlinear (in brief, PN) functions and optimal universal hash families are discussed. We point out the equivalence of constructions between them, i.e., from PN functions, one can obtain optimal universal hash families and vice versa. As an application of our construction, a message authentication code is proposed, which provides better resistance to substitution attack than a known construction given by Carlet et al. in 2006. More generally, the connections between functions with given differential uniformity and some universal hash families are studied.

In this study the authors propose a new multivariate hash function with HAsh Iterative FrAmework framework which we call the hash function quadratic polynomials multiplying linear polynomials (QML). The new hash function is made of cubic polynomials which are the products of quadratic polynomials and linear polynomials. The authors design the quadratic-polynomial part of the compression function based on the centre map of the multivariate public key cryptosystem Matsumoto-Imai cryptosystem (MI). The hash function QML can keep the three cryptography properties and be immune to the pre-image attack, second pre-image attack, collision attack, differential attack and algebraic attack. The required memory storage is about 50% of the one which is built of the cubic polynomials and their coefficients are random. On the avalanche effect, by experiments the authors get the result that about one half of the output bits are different when one input bit is changed randomly. The one-round diffusion of the hash function QML is twice of that of Blake. Also the authors simplify the matrixes of the new hash function, analyse the rationality and show the comparable data. Finally, the authors give the advice to the parameters of the new hash function and summarise the paper.

At the Cryptographic Hash Workshop hosted by NIST in 2005, Lee et al. proposed the DHA-256 (Double Hash Algorithm-256) hash function. The design of DHA-256 builds upon the design of SHA-256, but introduces additional strengthening features such as optimizing the message expansion and step function against local collision attacks. Previously, DHA-256 was analyzed by J. Zhong and X. Lai, who presented a preimage attack on 35 steps of the compression function with complexity 2^2^3^9^.^6. In addition, the IAIK Krypto Group provided evidence that there exists a 9-step local collision for the DHA-256 compression function with probability higher than previously predicted. In this paper, we analyze DHA-256 in the context of higher order differential attacks. In particular, we provide a practical distinguisher for 42 out of 64 steps and give an example of a colliding quartet to validate our results.

message that originated from an authorized user is defined as User Authentication and is provided by Message Authentication codes (MAC). The provision of assurance that the message is not been modified is defined as Message Authentication and is provided by Hash functions. Authenticated code is generated when MAC uses Hash function it is called Hash based MAC (HMAC). In this paper an algorithm is proposed for HMAC which uses SHA-2 as cryptographic hash function. The algorithm is implemented using GUI based controls in MATLAB toolbox which enables the algorithm to be friendly with the user. Theoretical analysis and experimentation show that this hash function is with high plaintext sensitivity and low collision resistance, and secure against birthday attacks or meet-in-the-middle attacks. These properties make it a suitable choice for data signature or authentication.

In this paper, the chaos-based hash function is analyzed, then an improved version of chaos-based hash function is presented and discussed using chaotic neural networks. It is based on the piecewise linear chaotic map that is used as a transfer function in the input and output of the neural network layer. The security of the improved hash function is also discussed and a novel type of collision resistant hash function called semi-collision attack is proposed, which is based on the collision percentage between the two hash values. In the proposed attack particle swarm optimization algorithm is used to define the fitness function parameters. Finally, numerical and simulation results provides strong collision resistance and high performance efficiency.

We present a collision and preimage security analysis of MDC-4, a 24-years-old construction for transforming an n-bit block cipher into a 2 n-bit hash function. We start with MDC-4 based on one single block cipher, and prove that any adversary with query access to the underlying block cipher requires at least 25n/4 queries (asymptotically) to find a collision. For the preimage resistance, we present a surprising negative result: for a target image with the same left and right half, a preimage for the full MDC-4 hash function can be found in 2n queries. Yet, restricted to target images with different left and right halves, we prove that at least 25n/4queries (asymptotically) are required to find a preimage. Next, we consider MDC-4 based on two independent block ciphers, a model that is less general but closer to the original design, and prove that the collision bound of 25n/8 queries and the preimage bound of 25n/4queries apply to the MDC-4 compression function and hash function design. With these results, we are the first to formally confirm that MDC-4 offers a higher level of provable security compared to MDC-2. © 2013 Springer Science+Business Media New York. ispartof: Designs, Codes and Cryptography vol:73 issue:1 pages:121-150 status: published

The cryptographic hash functions Extended MD4 and RIPEMD are double-branch hash functions, which consist of two parallel branches. Extended MD4 was proposed by Rivest in 1990, and RIPEMD was devised in the framework of the RIPE project (RACE Integrity Primitives Evaluation, 1988 ~ 1992). On the basis of differential analysis and meet-in-the-middle attack principle, this paper proposes a collision attack on the full Extended MD4 and a pseudo-preimage attack on the full RIPEMD respectively. The collision attack on Extended MD4 holds with a complexity of 237, and a collision instance is presented. The pseudo-preimage attack on RIPEMD holds with a complexity of 2125:4, which optimizes the complexity order for brute-force attack. The results in this study will also be beneficial to the analysis of other double-branch hash functions such as RIPEMD-160.

We constructed a hash function by using the idea of cayley graph, hash function based on computing a suitable matrix product in groups of the form SL2(F2 n ). We found collision between palindrome bit strings of length 2n+2 for the new construction. Here we reinforce the hash function by adding key to it and we claim that it will resists palindrome collision. Keywords - Cayley graph, Group, Hash function, Irreducible polynomial, Message Authentication Code, palindrome collision.

 Abstract—Many identity-based public key cryptosystems from bilinear pairings use hash functions to construct their public keys. Most of these schemes only specify the need of applying cryptographic strong or collision free hash functions, without giving any detail of which or what hash functions should be used. Traditional understanding of a cryptographic strong hash function has three security properties, which are pre-image resistance, second pre-image resistance and collision resistance. However, with only these three properties, in this paper we show a potential security vulnerability of identity-based cryptographic cryptosystems if the hash functions used are not correctly constructed. To fix this vulnerability, this paper defines an additional desirable security property for the hash functions in these identity-based cryptosystems.

We propose a class of almost rate-1 construction for 2n-bit hash functions, based on (2n, n) blockciphers, where 2n is the length of the cipher key and n is the cipher block length. These hash functions we proposed are proved to be optimum collision resistance and preimage resistance in the ideal cipher model. The hash rate of the construction is l−1/l where l is the number of cipher calls in the compression function. The hash rate is closed to 1 if l is large. Compare with existing DBL hash functions based on block ciphers with optimum collision resistance and preimage resistance, they are more efficient and simpler.

Secure hashes have an indispensable purpose to play in modern multimedia image encryptions. Traditional block ciphering techniques are quite complex, command colossal processing time for key generation and sometimes are a source of redundancy. This paper proposes to suggest a method for designing one-way cryptographic hash function and a block ciphering scheme based on proposed hash codes. In the proposed work, we have divided the message into blocks with each block individually processed by chaotic systems. The transitional hashes are created utilizing advanced control and input parameters. The two hash codes are utilized to create a final hash. The experimental outcomes justify striking performance of proposed chaotic hash method. Moreover, the generated hash code is applied for realizing an image block ciphering technique. The encryption process is plain-image dependent thereby exhibits satisfactory encryption effect suitable for practical applications.

In this paper we provide method a collision attack on all n-bit iterated hash functions with Merkle-Damgard construction use parallel algorithm, allowing a collision to be found for a 2n block message and k-sum of computer with about 2n/2/k work. Davies-Meyer scheme using SIMECK-32 algorithm as an example, our attack can find a collision for a 232 bit total output with 8 computer become 213 work for each computer. The result of this research is plaintext that meets the characteristics of fixed point that does not affect the plaintext hash value because the resulting output is the used IV value itself. Plaintext is used to construct collision. Apparently the result of the application of the Davies-Meyer scheme is not resistant to collision attack because there are three fixed point in the two IV samples which are used.

Collision resistance is one of the most important properties to ensure the safety of a hash function. In this paper, we tweak the quasigroup string transformation R and then give an infinite classes hash functions called “Edon”-R∗ on the base of “Edon”-R, which has a nice property of strongly collision free that can be proved mathematically and experimentally.

© 2015, Springer-Verlag Berlin Heidelberg. A well-established method of constructing hash functions is to base them on non-compressing primitives, such as one-way functions or permutations. In this work, we present S r , an rn-to-n-bit compression function (for r≥ 1) making 2 r- 1 calls to n-to-n-bit primitives (random functions or permutations). S r compresses its inputs at a rate (the amount of message blocks per primitive call) up to almost 1/2, and it outperforms all existing schemes with respect to rate and/or the size of underlying primitives. For instance, instantiated with the 1600 -bit permutation of NIST’s SHA-3 hash function standard, it offers about 800 -bit security at a rate of almost 1/2, while SHA-3-512 itself achieves only 512 -bit security at a rate of about 1/3. We prove that S r achieves asymptotically optimal collision security against semi-adaptive adversaries up to almost 2 n/2 queries and that it can be made preimage secure up to 2 n queries using a simple tweak. ispartof: International Journal of Information Security vol:15 issue:3 pages:285-300 status: published

Keccak Hash Function is the winner of SHA3 competition. Hash function collision has become one of the fundamental problem in Keccak Hash Function. One of the attack which is based on collision has been proposed by Plasencia, et.al. They proposed the practical analysis of reduced round Keccak Hash Function, such that the collision will be found in the second round of Keccak-224. For preventing Keccak Hash Function against Plasencia attack, denying collision in the second round is necessary. Denying the collision of Keccak Hash Function has become one challenge. Since the attacker used free bit for finding the collision, then for preventing against the attack the free bit camouflaging should be conducted. Therefore, for denying the collision in the second round of Keccak Hash Function, free bit camouflaging is proposed. Free bits are used to find the original message that is caused by the collision. For denying the collision, the proposed method modifies the input message by using reverse interleaving scheme. This scheme introduces inverse double mirror image sequence of a message to prevent the attacker in obtaining the original free bits. Based on the experiment, it has been proven that using reverse interleaving, the attacker obtained the camouflaged free bit instead of the original one. The camouflaged free bit will increase the difficulty for finding the collision such that the collision could not be found in the second round. This condition will prevent the attacker for finding the original message. The larger the difference would increase the complexity of attack on Keccak Hash Function in obtaining the original message.

We study the security of the concatenation combiner $$H_1M \Vert H_2M$$H1Mi¾?H2M for two independent iterated hash functions with n-bit outputs that are built using the Merkle-Damgard construction. In 2004 Joux showed that the concatenation combiner of hash functions with an n-bit internal state does not offer better collision and preimage resistance compared to a single strong n-bit hash function. On the other hand, the problem of devising second preimage attacks faster than $$2^n$$2n against this combiner has remained open since 2005 when Kelsey and Schneier showed that a single Merkle-Damgard hash function does not offer optimal second preimage resistance for long messages. In this paper, we develop new algorithms for cryptanalysis of hash combiners and use them to devise the first second preimage attack on the concatenation combiner. The attack finds second preimages faster than $$2^n$$2n for messages longer than $$2^{2n/7}$$22n/7 and has optimal complexity of $$2^{3n/4}$$23n/4. This shows that the concatenation of two Merkle-Damgard hash functions is not as strong a single ideal hash function. Our methods are also applicable to other well-studied combiners, and we use them to devise a new preimage attack with complexity of $$2^{2n/3}$$22n/3 on the XOR combiner $$H_1M \oplus H_2M$$H1Mi¾?H2M of two Merkle-Damgard hash functions. This improves upon the attack by Leurent and Wang presented at Eurocrypt 2015 whose complexity is $$2^{5n/6}$$25n/6 but unlike our attack is also applicable to HAIFA hash functions. Our algorithms exploit properties of random mappings generated by fixing the message block input to the compression functions of $$H_1$$H1 and $$H_2$$H2. Such random mappings have been widely used in cryptanalysis, but we exploit them in new ways to attack hash function combiners.