Iftach Haitner

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We consider two of the most fundamental theorems in Cryptography. The first, due to H̊astad et al. [HILL99], is that pseudorandom generators can be constructed from any one-way function. The second due to Yao [Yao82] states that the existence of weak one-way functions (i.e. functions on which every efficient algorithm fails to invert with some noticeable(More)
We give a new construction of pseudorandom generators from any one-way function. The construction achieves better parameters and is simpler than that given in the seminal work of Hastad, Impagliazzo, Levin, and Luby [SICOMP '99]. The key to our construction is a new notion of "next-block pseudoentropy", which is inspired by the notion of "inaccessible(More)
We study the round complexity of various cryptographic protocols. Our main result is a tight lower bound on the round complexity of any fully-black-box construction of a statistically-hiding commitment scheme from oneway permutations, and even front trapdoor permutations. This lower bound matches the round complexity of the statistically-hiding commitment(More)
We study the possibility of constructing encryption schemes secure under messages that are chosen depending on the key k of the encryption scheme itself. We give the following separation results that hold both in the private and in the public key settings: – Let H be the family of poly(n)-wise independent hash-functions. There exists no fully-black-box(More)
We give a construction of statistically-hiding commitment schemes (ones where the hiding propertyholds information theoretically), based on the minimal cryptographic assumption that one-way functions exist. Our construction employs two-phase commitment schemes, recently constructed by Nguyen, Ong and Vadhan (FOCS '06), and universal one-way hash functions(More)
We construct the rst public-key encryption scheme that is proven secure (in the standard model, under standard assumptions) even when the attacker gets access to encryptions of arbitrary e cient functions of the secret key. Speci cally, under either the DDH or LWE assumption, and for arbitrary but xed polynomials L and N , we obtain a public-key encryption(More)
We put forth a new computational notion of entropy, which measures the (in)feasibility of sampling high entropy strings that are consistent with a given protocol. Specifically, we say that the i'th round of a protocol (A,B) has *accessible entropy* at most k, if no polynomial-time strategy A* can generate messages for A such that the entropy of its message(More)
  • Iftach Haitner
  • 2009 50th Annual IEEE Symposium on Foundations of…
  • 2009
The question of whether or not parallel repetition reduces the soundness error is a fundamental question in the theory of protocols. While parallel repetition reduces (at an exponential rate) the error in interactive proofs and (at a weak exponential rate) in special cases of interactive arguments (e.g., 3-message protocols --- Bellare, Impagliazzo and Naor(More)
Interactive hashing, introduced by Naor, Ostrovsky, Venkatesan, and Yung (J. Cryptol. 11(2):87–108, 1998), plays an important role in many cryptographic protocols. In particular, interactive hashing is a major component in all known constructions of statistically hiding commitment schemes and of statistical zero-knowledge arguments based on general one-way(More)