aqora

On robust combiners for oblivious transfer and other primitives

Danny Harnik, Joe Kilian, Moni Naor +2 more

A (1,2)-robust combiner for a cryptographic primitive P is a construction that takes two candidate schemes for P and combines them into one scheme that securely implement P even if one of the candidates fails. Robust combiners are a useful tool for ensuring better security in applied cryptography, and also a handy tool for constructing cryptographic protocols. For example, we discuss using robust combiners for obtaining universal schemes for cryptographic primitives (a universal scheme is an explicit construction that implements P under the sole assumption that P exists). In this paper we study what primitives admit robust combiners. In addition to known and very simple combiners for one-way functions and equivalent primitives, we show robust combiners for protocols in the world of public key cryptography, namely for Key Agreement(KA). The main point we make is that things are not as nice for Oblivious Transfer (OT) and in general for secure computation. We prove that there are no “transparent black-box ” robust combiners for OT, giving an indication to the difficulty of finding combiners for OT. On the positive side we show a black box construction of a (2, 3)-robust combiner for OT, as well as a generic construction of (1, n)-robust OT-combiners from any (1, 2)-robust OT-combiner.A (1,2)-robust combiner for a cryptographic primitive P is a construction that takes two candidate schemes for P and combines them into one scheme that securely implement P even if one of the candidates fails. Robust combiners are a useful tool for ensuring better security in applied cryptography, and also a handy tool for constructing cryptographic protocols. For example, we discuss using robust combiners for obtaining universal schemes for cryptographic primitives (a universal scheme is an explicit construction that implements P under the sole assumption that P exists). In this paper we study what primitives admit robust combiners. In addition to known and very simple combiners for one-way functions and equivalent primitives, we show robust combiners for protocols in the world of public key cryptography, namely for Key Agreement(KA). The main point we make is that things are not as nice for Oblivious Transfer (OT) and in general for secure computation. We prove that there are no “transparent black-box ” robust combiners for OT, giving an indication to the difficulty of finding combiners for OT. On the positive side we show a black box construction of a (2, 3)-robust combiner for OT, as well as a generic construction of (1, n)-robust OT-combiners from any (1, 2)-robust OT-combiner.

Jan 1, 20051 citation

Secure Computation

Silvio M. Micali, Phillip Rogaway

Springer eBooksAug 11, 2007153 citations

Efficiently from Semi-honest to Malicious OT via OLFE.

Jürg Wullschleger

A combiner securely implements a functionality out of a set implementations of another functionality from which some may be insecure. We present two efficient combiners for oblivious linear function evaluation (OLFE). The first is a constant-rate OLFE combiner in the semihonest model, the second combiner implements Rabin string oblivious transfer (RabinOT) from OLFE in the malicious model. As an application, we show a very efficient reductions in the malicious model of RabinOT over strings to one-out-of-two oblivious transfer over bits (OT) that is only secure in the semihonest model. For string of size ℓ = ω(k 2), our reductions uses only 4ℓ + o(ℓ) instances of OT, while previous results required Ω(ℓk 2). Our new reduction leads to an efficiency improvement for general multi-party computation (MPC) based on semi-honest OT, and makes it almost as efficient as MPC based on malicious OT. All reductions are unconditionally secure, black-box, universally composable and secure against adaptive adversaries. 1 1A combiner securely implements a functionality out of a set implementations of another functionality from which some may be insecure. We present two efficient combiners for oblivious linear function evaluation (OLFE). The first is a constant-rate OLFE combiner in the semihonest model, the second combiner implements Rabin string oblivious transfer (RabinOT) from OLFE in the malicious model. As an application, we show a very efficient reductions in the malicious model of RabinOT over strings to one-out-of-two oblivious transfer over bits (OT) that is only secure in the semihonest model. For string of size ℓ = ω(k 2), our reductions uses only 4ℓ + o(ℓ) instances of OT, while previous results required Ω(ℓk 2). Our new reduction leads to an efficiency improvement for general multi-party computation (MPC) based on semi-honest OT, and makes it almost as efficient as MPC based on malicious OT. All reductions are unconditionally secure, black-box, universally composable and secure against adaptive adversaries. 1 1

Jan 1, 20091 citation

Combiners for Functional Encryption, Unconditionally

Aayush Jain, Nathan Manohar, Amit Sahai

Lecture notes in computer scienceJan 1, 202021 citations

Single-use ot combiners with near-optimal resilience

Yuval Ishai, Hemanta K. Maji, Amit Sahai +1 more

An oblivious transfer (OT) channel takes as input a pair of bits (s0, s1) from the sender and delivers (c, sc) to the receiver, where c ∈ {0, 1} is chosen uniformly at random. A secure implementation of such a channel hides c from the sender and s1-cfrom the receiver. These secrecy properties make OT channels very useful for cryptography; for example, they can be used to perform general secure multi-party computation.

IEEE International Symposium on Information Theory (ISIT)Jun 1, 201410 citations

Robuster Combiners for Oblivious Transfer

Remo Meier, Bartosz Przydatek, Jürg Wullschleger

Springer eBooksMay 16, 200742 citations

OT-Combiners via Secure Computation

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