LIPIcs, Volume 251, ITCS 2023, Complete Volume

LIPIcs, Volume 251, ITCS 2023, Complete Volum

LIPIcs, Volume 244, ESA 2022, Complete Volume

LIPIcs, Volume 244, ESA 2022, Complete Volum

Tools and Algorithms for the Construction and Analysis of Systems

This open access two-volume set constitutes the proceedings of the 27th International Conference on Tools and Algorithms for the Construction and Analysis of Systems, TACAS 2021, which was held during March 27 – April 1, 2021, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2021. The conference was planned to take place in Luxembourg and changed to an online format due to the COVID-19 pandemic. The total of 41 full papers presented in the proceedings was carefully reviewed and selected from 141 submissions. The volume also contains 7 tool papers; 6 Tool Demo papers, 9 SV-Comp Competition Papers. The papers are organized in topical sections as follows: Part I: Game Theory; SMT Verification; Probabilities; Timed Systems; Neural Networks; Analysis of Network Communication. Part II: Verification Techniques (not SMT); Case Studies; Proof Generation/Validation; Tool Papers; Tool Demo Papers; SV-Comp Tool Competition Papers

On Resilience to Computable Tampering

Non-malleable codes, introduced by Dziembowski, Pietrzak, and Wichs (ICS 2010), provide a means of encoding information such that if the encoding is tampered with, the result encodes something either identical or completely unrelated. Unlike error-correcting codes (for which the result of tampering must always be identical), non-malleable codes give guarantees even when tampering functions are allowed to change every symbol of a codeword. In this thesis, we will provide constructions of non-malleable codes secure against a variety tampering classes with natural computational semantics: • Bounded-Communication: Functions corresponding to 2-party protocols where each party receives half the input (respectively) and then may communicate </4 bits before returning their (respective) half of the tampered output. •Local Functions (Juntas):} each tampered output bit is only a function of n¹-ẟ inputs bits, where ẟ>0 is any constant (the efficiency of our code depends on ẟ). This class includes NC⁰. •Decision Trees: each tampered output bit is a function of n¹/⁴-⁰(¹) adaptively chosen bits. •Small-Depth Circuits: each tampered output bit is produced by a log(n)/log log(n)-depth circuit of polynomial size, for some constant . This class includes AC⁰. •Low Degree Polynomials: each tampered output field element is produced by a low-degree (relative to the field size) polynomial. •Polynomial-Size Circuit Tampering: each tampered codeword is produced by circuit of size ᶜ where is any constant (the efficiency of our code depends on ). This result assumes that E is hard for exponential size nondeterministic circuits (all other results are unconditional). We stress that our constructions are efficient (encoding and decoding can be performed in uniform polynomial time) and (with the exception of the last result, which assumes strong circuit lower bounds) enjoy unconditional, statistical security guarantees. We also illuminate some potential barriers to constructing codes for more complex computational classes from simpler assumptions