The Experts below are selected from a list of 8982 Experts worldwide ranked by ideXlab platform
Bart Preneel - One of the best experts on this subject based on the ideXlab platform.
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Cryptographic Hash Functions: Successes and Failures
2012Co-Authors: Bart PreneelAbstract:Cryptographic Hash functions are widely used in information security. Applications include the computation of a short unique identifier of a string (e.g. for a digital signature), hiding a string (e.g. for password protection), commiting to a string in a protocol, key derivation and for entropy extraction. In addition, they have been deployed to instantiate random oracles in a broad range of protocols. As Hash functions became available that were very efficient, they were also used as building blocks for block ciphers, MAC algorithms and even stream ciphers. Cryptographic Hash functions map input strings of arbitrary length to fixed length output strings. The main security properties required are preimage resistance, second preimage resistance, and collision resistance. Later on new properties were identified that include resistance against length extension attacks, partial preimage resistance and indifferentiability from a random oracle. Designing Hash functions turns out to be rather difficult. More than three quarters of all designs have been cryptanalyzed. This includes widely used Hash functions such as MD4, MD5 and SHA-1. In addition, during the last decade new structural attacks have been identified that show that widely used generic constructions have serious flaws. This talk will discuss some of these unexpected attacks, but will also show some positive results. More in particular, a growing number of results shows how security properties of Hash functions can be deduced from security properties of the building blocks, that are either ideal permutations, ideal block ciphers or ideal compression functions. While this still leaves open how to design secure building blocks, it simplifies the problem of Hash function design and increases our confidence in more recent Hash functions. For the long term, we face the challenging problem to design an efficient Hash function, the security of which can be reduced to an elegant mathematical problem. The talk will conclude with a brief overview of the NIST SHA-3 competition. More than 60 designs were evaluated during a 5-year open process to select a new US government Hash function standard. It is expected that the winner of the SHA-3 competition will be announced at the end of the Summer of 2012.
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Security Properties of Domain Extenders for Cryptographic Hash Functions
Journal of Information Processing Systems, 2010Co-Authors: Elena Andreeva, Bart Mennink, Bart PreneelAbstract:Cryptographic Hash functions reduce inputs of arbitrary or very large length to a short string of fixed length. All Hash function designs start from a compression function with fixed length inputs. The compression function itself is designed from scratch, or derived from a block cipher or a permutation. The most common procedure to extend the domain of a compression function in order to obtain a Hash function is a simple linear iteration; however, some variants use multiple iterations or a tree structure that allows for parallelism. This paper presents a survey of 17 extenders in the literature. It considers the natural question whether these preserve the security properties of the compression function, and more in particular collision resistance, second preimage resistance, preimage resistance and the pseudo-random oracle property.
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Cryptographic Hash functions theory and practice
International Conference on Cryptology in India, 2010Co-Authors: Bart PreneelAbstract:Cryptographic Hash functions are an essential building block for security applications. Until 2005, the amount of theoretical research and cryptanalysis invested in this topic was rather limited. From the hundred designs published before 2005, about 80% was cryptanalyzed; this includes widely used Hash functions such as MD4 and MD5. Moreover, serious shortcomings have been identified in the theoretical foundations of existing designs. In response to this Hash function crisis, a large number of papers has been published with theoretical results and novel designs. In November 2007, NIST announced the start of the SHA-3 competition, with as goal to select a new Hash function family by 2012. About half of the 64 submissions were broken within months. We present a brief outline of the state of the art of Hash functions half-way the competition and attempt to identify open research issues.
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Cryptographic Hash functions
European Transactions on Telecommunications, 2010Co-Authors: Bart PreneelAbstract:Hash functions were introduced in cryptology in the late seventies as a tool to protect the authenticity of information. Soon it became clear that they were a very useful building block to solve other security problems in telecommunication and computer networks. This paper sketches the history of the concept, discusses the applications of Hash functions, and presents the approaches that have been followed to construct Hash functions. In addition, it tries to provide the information which is necessary to choose a practical Hash function. An overview of practical constructions and their performance is given and some attacks are discussed. Special attention is paid to standards dealing with Hash functions.
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Cryptographic Hash Functions: Theory and Practice
Lecture Notes in Computer Science, 2010Co-Authors: Bart PreneelAbstract:Cryptographic Hash functions are an essential building block for security applications. Until 2005, the amount of theoretical research and cryptanalysis invested in this topic was rather limited. From the hundred designs published before 2005, about 80% was cryptanalyzed; this includes widely used Hash functions such as MD4 and MD5. Moreover, serious shortcomings have been identified in the theoretical foundations of existing designs. In response to this Hash function crisis, a large number of papers has been published with theoretical results and novel designs. In November 2007, NIST announced the start of the SHA-3 competition, with as goal to select a new Hash function family by 2012. About half of the 64 submissions were broken within months. This talk will present an outline of the state of the art of Hash functions half-way the competition and attempts to identify open research issues.
Mohammad Abdulateef Alahmad - One of the best experts on this subject based on the ideXlab platform.
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security of a new Cryptographic Hash function titanium
Indonesian Journal of Electrical Engineering and Computer Science, 2018Co-Authors: Abdullah Nazeeh Saleh, Mohammad Abdulateef AlahmadAbstract:This paper introduces the security analysis of Titanium Hash function that uses SF block cipher and follows sponge construction. A brief description of the sponge function and the design choice of Titanium are introduced. Basic security criteria of random function have been presented and studied on Titanium and then, differential cryptanalysis on Titanium has been performed and showed the resistance of it on the most recent differential attacks. A table of security discussions finalizes the paper and describes the complexity of Titanium on brute force cryptanalysis.
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design of a new Cryptographic Hash function titanium
Indonesian Journal of Electrical Engineering and Computer Science, 2018Co-Authors: Mohammad Abdulateef AlahmadAbstract:This paper introduces a new Cryptographic Hash function that follows sponge construction. Paper begins with outlining the structure of the construction. Next part describes the functionality of Titanium and cipher used. A competition between block cipher and stream cipher is presented and showed the reason of using block cipher rather than stream cipher. Speed performance is calculated and analyzed using state-of-art CPUs.
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double a a new Cryptographic Hash function its design
Journal of Advanced Computer Science and Technology, 2017Co-Authors: Abdullah Issa, Mohammad Abdulateef Alahmad, Abdullah AlsalehAbstract:This paper examines the outline decisions of the sponge constructed Cryptographic Hash function Double-A. Firstly, the relative favorable circumstances of why a stream mode cipher is utilized instead of a block mode are given. Furthermore, a portrayal of what a sponge function is, the way it is designed and what are its fundamental components. At long last, after a brief review of the Salsa20 stream cipher and its structure, the decisions of the states width, rounds and operations in the pseudorandom function f are talked about in subtle element to show how and why they are utilized as a part of the stage of Double-A.
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a new design of Cryptographic Hash function gear
International Journal on Perceptive and Cognitive Computing, 2016Co-Authors: Abdulaziz Ali Alkandari, Imad Fakhri Alshaikhli, Khalil Ibrahim Alkandari, Mohammad Abdulateef AlahmadAbstract:A Hash function is any function that can be used to map data of arbitrary size to data of fixed size. A Hash function usually has two main components: a permutation function or compression function and mode of operation. We will propose a new concrete novel design of a permutation based Hash functions called Gear in this paper. It is a Hash function based on block cipher in Davies-Meyer mode. It uses the patched version of Merkle-Damgard, i.e. the wide pipe construction as its mode of operation. Thus, the intermediate chaining value has at least twice larger length than the output Hash. And the permutations functions used in Gear are inspired from the SHA-3 finalist Groestl Hash function which is originally inspired from Rijndael design (AES). There is a very strong confusion and diffusion in Gear as a result.
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Broad View of Cryptographic Hash Functions
2013Co-Authors: Mohammad Abdulateef Alahmad, Imad Fakhri AlshaikhliAbstract:Cryptographic Hash function is a function that takes an arbitrary length as an input and produces a fixed size of an output. The viability of using Cryptographic Hash function is to verify data integrity and sender identity or source of information. This paper provides a detailed overview of Cryptographic Hash functions. It includes the properties, classification, constructions, attacks, applications and an overview of a selected dedicated Cryptographic Hash functions.
Jacques Stern - One of the best experts on this subject based on the ideXlab platform.
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on the length of Cryptographic Hash values used in identification schemes
International Cryptology Conference, 1994Co-Authors: Marc Girault, Jacques SternAbstract:Many interactive identification schemes based on the zero-knowledge concept use Cryptographic Hash-values, either in their basic design or in specific variants. In this paper, we first show that 64-bit Hash-values, a length often suggested, definitely decrease the level of the security of all these schemes. (Of course, this does not compromise the security of the schemes by themselves). Then we prove that collision-resistance is a sufficient condition to achieve the claimed level of security. Finally, by using a weaker notion of collision-resistance, we present interesting variants of some of these schemes (in particular the Schnorr and the Guillou-Quisquater schemes) which minimize the number of communication bits for a given level of security.
Mihir Bellare - One of the best experts on this subject based on the ideXlab platform.
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New approaches for the design and analysis of Cryptographic Hash functions
2013Co-Authors: Mihir Bellare, Thomas RistenpartAbstract:Cryptographic Hash functions deterministically generate a short digest "summary" of an input message. Their functionality and perceived security properties have contributed to their use in a wide variety of applications. Unfortunately, traditional design approaches for Hash functions target only a single application. This gap between use and design has lead to Hash functions not providing the security properties required by certain uses, and, in turn, to vulnerabilities in applications. This thesis argues for the construction of multi-property Hash functions. Such a function should enjoy strong guarantees that it simultaneously provides multiple, disparate security properties, while remaining efficient and easy to use. That is, these Hash functions are built to reflect the diverse needs of applications. Towards this end, we introduce the notion of a multi-property-preserving domain extension transform, which formalizes the goal of multi-property Hashing for a key step in Hash design. By analyzing existing transforms from the lense of multiproperty-preservation, we explain the inability of traditional Hash designs to be multi-property. We propose new domain extension transforms, provide new techniques for their formal analysis in modern cryptography's framework of provable security, and use the techniques to show that the proposed constructions provide the multi-property-preservation guarantees needed to build the next generation of Hash functions.
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HMAC: Keyed-Hashing for Message Authentication
1997Co-Authors: Hugo Krawczyk, Mihir Bellare, Ran CanettiAbstract:This document describes HMAC, a mechanism for message authentication using Cryptographic Hash functions. HMAC can be used with any iterative Cryptographic Hash function, e.g., MD5, SHA-1, in combination with a secret shared key. The Cryptographic strength of HMAC depends on the properties of the underlying Hash function.
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keying Hash functions for message authentication
International Cryptology Conference, 1996Co-Authors: Mihir Bellare, Ran Canetti, Hugo KrawczykAbstract:The use of Cryptographic Hash functions like MD5 or SHA-1 for message authentication has become a standard approach in many applications, particularly Internet security protocols. Though very easy to implement, these mechanisms are usually based on ad hoc techniques that lack a sound security analysis. We present new, simple, and practical constructions of message authentication schemes based on a Cryptographic Hash function. Our schemes, NMAC and HMAC, are proven to be secure as long as the underlying Hash function has some reasonable Cryptographic strengths. Moreover we show, in a quantitative way, that the schemes retain almost all the security of the underlying Hash function. The performance of our schemes is essentially that of the underlying Hash function. Moreover they use the Hash function (or its compression function) as a black box, so that widely available library code or hardwair can be used to implement them in a simple way, and replaceability of the underlying Hash function is easily supported.
Hugo Krawczyk - One of the best experts on this subject based on the ideXlab platform.
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HMAC: Keyed-Hashing for Message Authentication
1997Co-Authors: Hugo Krawczyk, Mihir Bellare, Ran CanettiAbstract:This document describes HMAC, a mechanism for message authentication using Cryptographic Hash functions. HMAC can be used with any iterative Cryptographic Hash function, e.g., MD5, SHA-1, in combination with a secret shared key. The Cryptographic strength of HMAC depends on the properties of the underlying Hash function.
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keying Hash functions for message authentication
International Cryptology Conference, 1996Co-Authors: Mihir Bellare, Ran Canetti, Hugo KrawczykAbstract:The use of Cryptographic Hash functions like MD5 or SHA-1 for message authentication has become a standard approach in many applications, particularly Internet security protocols. Though very easy to implement, these mechanisms are usually based on ad hoc techniques that lack a sound security analysis. We present new, simple, and practical constructions of message authentication schemes based on a Cryptographic Hash function. Our schemes, NMAC and HMAC, are proven to be secure as long as the underlying Hash function has some reasonable Cryptographic strengths. Moreover we show, in a quantitative way, that the schemes retain almost all the security of the underlying Hash function. The performance of our schemes is essentially that of the underlying Hash function. Moreover they use the Hash function (or its compression function) as a black box, so that widely available library code or hardwair can be used to implement them in a simple way, and replaceability of the underlying Hash function is easily supported.