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Constructing cryptographic hash functions from fixedkey blockciphers. Full version of this paper
, 2008
"... Abstract. We propose a family of compression functions built from fixedkey blockciphers and investigate their collision and preimage security in the idealcipher model. The constructions have security approaching and in many cases equaling the security upper bounds found in previous work of the aut ..."
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Cited by 18 (5 self)
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Abstract. We propose a family of compression functions built from fixedkey blockciphers and investigate their collision and preimage security in the idealcipher model. The constructions have security approaching and in many cases equaling the security upper bounds found in previous work of the authors [24]. In particular, we describe a 2nbit to nbit compression function using three nbit permutation calls that has collision security N 0.5,whereN =2 n, and we describe 3nbit to 2nbit compression functions using five and six permutation calls and having collision security of at least N 0.55 and N 0.63. Key words: blockcipherbased hashing, collisionresistant hashing, compression functions, cryptographic hash functions, idealcipher model. 1
Building a collisionresistant compression function from noncompressing primitives
 In ICALP 2008, Part II
, 2008
"... Abstract. We consider how to build an efficient compression function from a small number of random, noncompressing primitives. Our main goal is to achieve a level of collision resistance as close as possible to the optimal birthday bound. We present a 2nton bit compression function based on three ..."
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Cited by 15 (3 self)
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Abstract. We consider how to build an efficient compression function from a small number of random, noncompressing primitives. Our main goal is to achieve a level of collision resistance as close as possible to the optimal birthday bound. We present a 2nton bit compression function based on three independent nton bit random functions, each called only once. We show that if the three random functions are treated as black boxes then finding collisions requires Θ(2 n/2 /n c) queries for c ≈ 1. This result remains valid if two of the three random functions are replaced by a fixedkey ideal cipher in DaviesMeyer mode (i.e., EK(x) ⊕ x for permutation EK). We also give a heuristic, backed by experimental results, suggesting that the security loss is at most four bits for block sizes up to 256 bits. We believe this is the best result to date on the matter of building a collisionresistant compression function from noncompressing functions. It also relates to an open question from Black et al. (Eurocrypt’05), who showed that compression functions that invoke a single noncompressing random function cannot suffice. We also explore the relationship of our problem with that of doubling the output of a hash function and we show how our compression function can be used to double the output length of ideal hashes.
Security/Efficiency Tradeoffs for PermutationBased Hashing
"... Abstract. We provide attacks and analysis that capture a tradeoff, in the idealpermutation model, between the speed of a permutationbased hash function and its potential security. We show that any 2nbit to nbit compression function will have unacceptable collision resistance it makes fewer than ..."
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Cited by 10 (2 self)
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Abstract. We provide attacks and analysis that capture a tradeoff, in the idealpermutation model, between the speed of a permutationbased hash function and its potential security. We show that any 2nbit to nbit compression function will have unacceptable collision resistance it makes fewer than three nbit permutation invocations, and any 3nbit to 2nbit compression function will have unacceptable security if it makes fewer than five nbit permutation invocations. Any rateα hash function built from nbit permutations can be broken, in the sense of finding preimages as well as collisions, in about N 1−α queries, where N =2 n. Our results provide guidance when trying to design or analyze a permutationbased hash function about the limits of what can possibly be done. 1
Hash Functions Based on Block Ciphers and Quaternary Codes
 Advances in Cryptology ASIACRYPT
, 1996
"... . We consider constructions for cryptographic hash functions based on mbit block ciphers. First we present a new attack on the LOKIDBH mode: the attack finds collisions in 2 3m=4 encryptions, which should be compared to 2 m encryptions for a brute force attack. This attack breaks the last remai ..."
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Cited by 9 (1 self)
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. We consider constructions for cryptographic hash functions based on mbit block ciphers. First we present a new attack on the LOKIDBH mode: the attack finds collisions in 2 3m=4 encryptions, which should be compared to 2 m encryptions for a brute force attack. This attack breaks the last remaining subclass in a wide class of efficient hash functions which have been proposed in the literature. We then analyze hash functions based on a collision resistant compression function for which finding a collision requires at least 2 m encryptions, providing a lower bound of the complexity of collisions of the hash function. A new class of constructions is proposed, based on error correcting codes over GF(2 2 ) and a proof of security is given, which relates their security to that of single block hash functions. For example, a compression function is presented which requires about 4 encryptions to hash an mbit block, and for which finding a collision requires at least 2 m encryptions...