TY - GEN
T1 - Oblivious Transfer with Constant Computational Overhead
AU - Boyle, Elette
AU - Couteau, Geoffroy
AU - Gilboa, Niv
AU - Ishai, Yuval
AU - Kohl, Lisa
AU - Resch, Nicolas
AU - Scholl, Peter
N1 - Publisher Copyright:
© 2023, International Association for Cryptologic Research.
PY - 2023/1/1
Y1 - 2023/1/1
N2 - The computational overhead of a cryptographic task is the asymptotic ratio between the computational cost of securely realizing the task and that of realizing the task with no security at all. Ishai, Kushilevitz, Ostrovsky, and Sahai (STOC 2008) showed that secure two-party computation of Boolean circuits can be realized with constant computational overhead, independent of the desired level of security, assuming the existence of an oblivious transfer (OT) protocol and a local pseudorandom generator (PRG). However, this only applies to the case of semi-honest parties. A central open question in the area is the possibility of a similar result for malicious parties. This question is open even for the simpler task of securely realizing many instances of a constant-size function, such as OT of bits. We settle the question in the affirmative for the case of OT, assuming: (1) a standard OT protocol, (2) a slightly stronger “correlation-robust" variant of a local PRG, and (3) a standard sparse variant of the Learning Parity with Noise (LPN) assumption. An optimized version of our construction requires fewer than 100 bit operations per party per bit-OT. For 128-bit security, this improves over the best previous protocols by 1–2 orders of magnitude. We achieve this by constructing a constant-overhead pseudorandom correlation generator (PCG) for the bit-OT correlation. Such a PCG generates N pseudorandom instances of bit-OT by locally expanding short, correlated seeds. As a result, we get an end-to-end protocol for generating N pseudorandom instances of bit-OT with o(N) communication, O(N) computation, and security that scales sub-exponentially with N. Finally, we present applications of our main result to realizing other secure computation tasks with constant computational overhead. These include protocols for general circuits with a relaxed notion of security against malicious parties, protocols for realizing N instances of natural constant-size functions, and reducing the main open question to a potentially simpler question about fault-tolerant computation.
AB - The computational overhead of a cryptographic task is the asymptotic ratio between the computational cost of securely realizing the task and that of realizing the task with no security at all. Ishai, Kushilevitz, Ostrovsky, and Sahai (STOC 2008) showed that secure two-party computation of Boolean circuits can be realized with constant computational overhead, independent of the desired level of security, assuming the existence of an oblivious transfer (OT) protocol and a local pseudorandom generator (PRG). However, this only applies to the case of semi-honest parties. A central open question in the area is the possibility of a similar result for malicious parties. This question is open even for the simpler task of securely realizing many instances of a constant-size function, such as OT of bits. We settle the question in the affirmative for the case of OT, assuming: (1) a standard OT protocol, (2) a slightly stronger “correlation-robust" variant of a local PRG, and (3) a standard sparse variant of the Learning Parity with Noise (LPN) assumption. An optimized version of our construction requires fewer than 100 bit operations per party per bit-OT. For 128-bit security, this improves over the best previous protocols by 1–2 orders of magnitude. We achieve this by constructing a constant-overhead pseudorandom correlation generator (PCG) for the bit-OT correlation. Such a PCG generates N pseudorandom instances of bit-OT by locally expanding short, correlated seeds. As a result, we get an end-to-end protocol for generating N pseudorandom instances of bit-OT with o(N) communication, O(N) computation, and security that scales sub-exponentially with N. Finally, we present applications of our main result to realizing other secure computation tasks with constant computational overhead. These include protocols for general circuits with a relaxed notion of security against malicious parties, protocols for realizing N instances of natural constant-size functions, and reducing the main open question to a potentially simpler question about fault-tolerant computation.
UR - https://www.scopus.com/pages/publications/85161423809
U2 - 10.1007/978-3-031-30545-0_10
DO - 10.1007/978-3-031-30545-0_10
M3 - Conference contribution
AN - SCOPUS:85161423809
SN - 9783031305443
T3 - Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
SP - 271
EP - 302
BT - Advances in Cryptology – EUROCRYPT 2023 - 42nd Annual International Conference on the Theory and Applications of Cryptographic Techniques, Proceedings
A2 - Hazay, Carmit
A2 - Stam, Martijn
PB - Springer Science and Business Media Deutschland GmbH
T2 - 42nd Annual International Conference on the Theory and Applications of Cryptographic Techniques, Eurocrypt 2023
Y2 - 23 April 2023 through 27 April 2023
ER -