Cryptology ePrint Archive: Report 2021/979

Constant-Overhead Zero-Knowledge for RAM Programs

Nicholas Franzese and Jonathan Katz and Steve Lu and Rafail Ostrovsky and Xiao Wang and Chenkai Weng

Abstract: We show a constant-overhead interactive zero-knowledge (ZK) proof system for RAM programs, that is, a ZK proof in which the communication complexity as well as the running times of the prover and verifier scale linearly in the size of the memory $N$ and the running time $T$ of the underlying RAM program. Besides yielding an asymptotic improvement of prior work, our implementation gives concrete performance improvements for RAM-based ZK proofs. In particular, our implementation supports ZK proofs of private read/write accesses to 64 MB of memory ($2^{24}$ 32-bit words) using only 34 bytes of communication per access, a more than $80\times$ improvement compared to the recent BubbleRAM protocol. We also design a lightweight RISC CPU that can efficiently emulate the MIPS-I instruction set, and for which our ZK proof communicates only $\approx$ 320 bytes per cycle, more than $10\times$ less than the BubbleRAM CPU. In a 100 Mbps network, we can perform zero-knowledge executions of our CPU (with 64 MB of main memory and 4 MB of program memory) at a clock rate of 6.6 kHz.

Category / Keywords: cryptographic protocols / zero-knowledge proofs

Original Publication (with minor differences): ACM CCS 2021

Date: received 21 Jul 2021, last revised 11 Sep 2021

Contact author: wangxiao at cs northwestern edu

Available format(s): PDF | BibTeX Citation

Version: 20210911:173411 (All versions of this report)

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