{"title":"Growth and irreducibility in path-incompressible trees","authors":"George Barmpalias, Xiaoyan Zhang","doi":"10.1016/j.ic.2024.105136","DOIUrl":"10.1016/j.ic.2024.105136","url":null,"abstract":"<div><p>We study randomness-preserving transformations of path-incompressible trees, namely trees of finite randomness deficiency. We characterize their branching density, and show: (a) sparse perfect path-incompressible trees can be effectively densified, almost surely; (b) there exists a path-incompressible tree with infinitely many paths which does not compute any perfect path-incompressible tree with computable oracle-use.</p></div>","PeriodicalId":54985,"journal":{"name":"Information and Computation","volume":"297 ","pages":"Article 105136"},"PeriodicalIF":1.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139413172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wenjie Bai, Jeremiah Blocki, Mohammad Hassan Ameri
{"title":"Cost-asymmetric memory hard password hashing","authors":"Wenjie Bai, Jeremiah Blocki, Mohammad Hassan Ameri","doi":"10.1016/j.ic.2023.105134","DOIUrl":"10.1016/j.ic.2023.105134","url":null,"abstract":"<div><p>In the past decade billions of user passwords have been exposed to the dangerous threat of offline password cracking<span> attacks. An offline attacker who has stolen the cryptographic hash<span> of a user's password can check as many password guesses as s/he likes limited only by the resources that s/he is willing to invest to crack the password. Pepper and key-stretching are two techniques that have been proposed to deter an offline attacker by increasing guessing costs. Pepper ensures that the cost of rejecting an incorrect password guess is higher than the (expected) cost of verifying a correct password guess. This is useful because most of the offline attacker's guesses will be incorrect. Unfortunately, as we observe the traditional peppering defense seems to be incompatible with modern memory hard key-stretching algorithms such as Argon2 or Scrypt. We introduce an alternative to pepper which we call Cost-Asymmetric Memory Hard Password Authentication which benefits from the same cost-asymmetry as the classical peppering defense i.e., the cost of rejecting an incorrect password guess is larger than the expected cost to authenticate a correct password guess. When configured properly we prove that our mechanism can only reduce the percentage of user passwords that are cracked by a rational offline attacker whose goal is to maximize (expected) profit i.e., the total value of cracked passwords minus the total guessing costs. We evaluate the effectiveness of our mechanism on empirical password datasets against a rational offline attacker. Our empirical analysis shows that our mechanism can reduce the percentage of user passwords that are cracked by a rational attacker by up to 10%.</span></span></p></div>","PeriodicalId":54985,"journal":{"name":"Information and Computation","volume":"297 ","pages":"Article 105134"},"PeriodicalIF":1.0,"publicationDate":"2024-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139093385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The membership problem for subsemigroups of GL2(Z) is NP-complete","authors":"Paul C. Bell , Mika Hirvensalo , Igor Potapov","doi":"10.1016/j.ic.2023.105132","DOIUrl":"10.1016/j.ic.2023.105132","url":null,"abstract":"<div><p>We show that the problem of determining if the identity matrix belongs to a finitely generated semigroup of <span><math><mn>2</mn><mo>×</mo><mn>2</mn></math></span> matrices from the General Linear Group <span><math><msub><mrow><mtext>GL</mtext></mrow><mrow><mn>2</mn></mrow></msub><mo>(</mo><mi>Z</mi><mo>)</mo></math></span> is solvable in <strong>NP</strong>. We extend this to prove that the membership problem is decidable in <strong>NP</strong> for <span><math><msub><mrow><mtext>GL</mtext></mrow><mrow><mn>2</mn></mrow></msub><mo>(</mo><mi>Z</mi><mo>)</mo></math></span> and for any arbitrary regular expression over matrices from the Special Linear group <span><math><msub><mrow><mtext>SL</mtext></mrow><mrow><mn>2</mn></mrow></msub><mo>(</mo><mi>Z</mi><mo>)</mo></math></span>. We show that determining if a given finite set of matrices from <span><math><msub><mrow><mtext>SL</mtext></mrow><mrow><mn>2</mn></mrow></msub><mo>(</mo><mi>Z</mi><mo>)</mo></math></span> or the modular group <span><math><msub><mrow><mtext>PSL</mtext></mrow><mrow><mn>2</mn></mrow></msub><mo>(</mo><mi>Z</mi><mo>)</mo></math></span> generates a group or a free semigroup are decidable in <strong>NP</strong>. Previous algorithms, shown in 2005 by Choffrut and Karhumäki, were in <strong>EXPSPACE</strong>. Our algorithm is based on new techniques allowing us to operate on compressed word representations of matrices without explicit expansions. When combined with known <strong>NP</strong>-hard lower bounds, this proves that the membership problem over <span><math><msub><mrow><mtext>GL</mtext></mrow><mrow><mn>2</mn></mrow></msub><mo>(</mo><mi>Z</mi><mo>)</mo></math></span> is <strong>NP</strong>-complete, and the group problem and the non-freeness problem in <span><math><msub><mrow><mtext>SL</mtext></mrow><mrow><mn>2</mn></mrow></msub><mo>(</mo><mi>Z</mi><mo>)</mo></math></span> are <strong>NP</strong>-complete. <span><sup>1</sup></span></p></div>","PeriodicalId":54985,"journal":{"name":"Information and Computation","volume":"296 ","pages":"Article 105132"},"PeriodicalIF":1.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0890540123001359/pdfft?md5=59ba4ebf4d7f374b59781f7656883bdb&pid=1-s2.0-S0890540123001359-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139031197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Special Issue on 13th International Conference on Security and Cryptography for Networks (SCN 2022)","authors":"Clemente Galdi , Stanislaw Jarecki","doi":"10.1016/j.ic.2023.105135","DOIUrl":"https://doi.org/10.1016/j.ic.2023.105135","url":null,"abstract":"","PeriodicalId":54985,"journal":{"name":"Information and Computation","volume":"296 ","pages":"Article 105135"},"PeriodicalIF":1.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139433906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Complexity of manipulation and bribery in premise-based judgment aggregation with simple formulas","authors":"Robert Bredereck , Junjie Luo","doi":"10.1016/j.ic.2023.105128","DOIUrl":"10.1016/j.ic.2023.105128","url":null,"abstract":"<div><p>Judgment aggregation is a framework to aggregate individual opinions on multiple, logically connected issues into a collective outcome. It is open to manipulative attacks such as <span>Manipulation</span> where judges (e.g., referees, experts, or jurors) cast their judgments strategically. Previous works have shown that most computational problems corresponding to these manipulative attacks are <span><math><mtext>NP</mtext></math></span>-hard. This desired computational barrier, however, often relies on formulas that are either of unbounded size or of complex structure.</p><p><span>We revisit the computational complexity for various </span><span>Manipulation</span> and <span>Bribery</span> problems in premise-based judgment aggregation, now focusing on simple and realistic formulas. We restrict all formulas to be clauses that are monotone, Horn-clauses, or have bounded length. We show that these restrictions make several variants of <span>Manipulation</span> and <span>Bribery</span>, which were in general known to be <span><math><mtext>NP</mtext></math></span>-hard, polynomial-time solvable. Moreover, we provide a P vs. NP dichotomy for a large class of clause restrictions (generalizing monotone and Horn clauses).</p></div>","PeriodicalId":54985,"journal":{"name":"Information and Computation","volume":"296 ","pages":"Article 105128"},"PeriodicalIF":1.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138516740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ilaria Chillotti , Emmanuela Orsini , Peter Scholl , Barry Van Leeuwen
{"title":"Scooby: Improved multi-party homomorphic secret sharing based on FHE","authors":"Ilaria Chillotti , Emmanuela Orsini , Peter Scholl , Barry Van Leeuwen","doi":"10.1016/j.ic.2023.105133","DOIUrl":"10.1016/j.ic.2023.105133","url":null,"abstract":"<div><p>In this paper we present new constructions of multi-party homomorphic secret sharing (HSS) based on a new primitive that we call <em>homomorphic encryption with decryption to shares</em> (HEDS). Our first scheme, which we call <span><math><mi>Scooby</mi></math></span>, is based on many popular fully homomorphic encryption (FHE) schemes with a linear decryption property. <span><math><mi>Scooby</mi></math></span> achieves an <em>n</em>-party HSS for general circuits with complexity <span><math><mi>O</mi><mo>(</mo><mo>|</mo><mi>F</mi><mo>|</mo><mo>+</mo><mi>log</mi><mo></mo><mi>n</mi><mo>)</mo></math></span>, as opposed to <span><math><mi>O</mi><mo>(</mo><msup><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>⋅</mo><mo>|</mo><mi>F</mi><mo>|</mo><mo>)</mo></math></span> for the prior best construction based on multi-key FHE. <span><math><mi>Scooby</mi></math></span> relies on a trusted setup procedure, and can be based on (ring)-LWE with a super-polynomial modulus-to-noise ratio. In our second construction, <span><math><mi>Scrappy</mi></math></span>, assuming any generic FHE plus HSS for NC1-circuits, we obtain a HEDS scheme which does not require a super-polynomial modulus. While these schemes all require FHE, in another instantiation, <span><math><mi>Shaggy</mi></math></span>, we show how it is also possible to obtain multi-party HSS without FHE, instead relying on the DCR assumption to obtain 4-party HSS for constant-degree polynomials.</p></div>","PeriodicalId":54985,"journal":{"name":"Information and Computation","volume":"297 ","pages":"Article 105133"},"PeriodicalIF":1.0,"publicationDate":"2023-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139067135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Functionality of compositions of top-down tree transducers is decidable","authors":"Sebastian Maneth , Helmut Seidl , Martin Vu","doi":"10.1016/j.ic.2023.105131","DOIUrl":"10.1016/j.ic.2023.105131","url":null,"abstract":"<div><p>We prove that functionality of compositions of top-down tree transducers is decidable by reducing the problem to the functionality of one top-down tree transducer with look-ahead.</p></div>","PeriodicalId":54985,"journal":{"name":"Information and Computation","volume":"296 ","pages":"Article 105131"},"PeriodicalIF":1.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0890540123001347/pdfft?md5=c1f9811d1a32918904a0b19f756bec2f&pid=1-s2.0-S0890540123001347-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138685102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Towards non-iterative calculation of the zeros of the Riemann zeta function","authors":"Yu. Matiyasevich","doi":"10.1016/j.ic.2023.105130","DOIUrl":"10.1016/j.ic.2023.105130","url":null,"abstract":"<div><p>We introduce a family of rational functions <span><math><msub><mrow><mi>R</mi></mrow><mrow><mi>N</mi></mrow></msub><mo>(</mo><mi>a</mi><mo>,</mo><msub><mrow><mi>d</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>,</mo><mspace></mspace><msub><mrow><mi>d</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mspace></mspace><mo>…</mo><mo>,</mo><mspace></mspace><msub><mrow><mi>d</mi></mrow><mrow><mi>N</mi></mrow></msub><mo>)</mo></math></span> with the following property. Let <span><math><msub><mrow><mi>d</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>,</mo><mspace></mspace><msub><mrow><mi>d</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mspace></mspace><mo>…</mo><mo>,</mo><mspace></mspace><msub><mrow><mi>d</mi></mrow><mrow><mi>N</mi></mrow></msub></math></span> be equal respectively to the value of some function <span><math><mi>f</mi><mo>(</mo><mi>s</mi><mo>)</mo></math></span> and the values of its first <em>N</em> derivatives calculated at a certain complex number <em>a</em> lying not too far from a zero <em>ρ</em> of this function. It is <em>expected</em> that the value of <span><math><msub><mrow><mi>R</mi></mrow><mrow><mi>N</mi></mrow></msub><mo>(</mo><mi>a</mi><mo>,</mo><msub><mrow><mi>d</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>,</mo><mspace></mspace><msub><mrow><mi>d</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mspace></mspace><mo>…</mo><mo>,</mo><mspace></mspace><msub><mrow><mi>d</mi></mrow><mrow><mi>N</mi></mrow></msub><mo>)</mo></math></span> is very close to <em>ρ</em>.</p><p><span>We demonstrate this phenomenon on several numerical instances with the Riemann zeta function in the role of </span><span><math><mi>f</mi><mo>(</mo><mi>s</mi><mo>)</mo></math></span>. For example, for <span><math><mi>N</mi><mo>=</mo><mn>10</mn></math></span> and <span><math><mi>a</mi><mo>=</mo><mn>0.6</mn><mo>+</mo><mn>14</mn><mi>i</mi></math></span> we have <span><math><mo>|</mo><msub><mrow><mi>R</mi></mrow><mrow><mn>10</mn></mrow></msub><mo>(</mo><mi>a</mi><mo>,</mo><msub><mrow><mi>d</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>,</mo><mspace></mspace><msub><mrow><mi>d</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mspace></mspace><mo>…</mo><mo>,</mo><mspace></mspace><msub><mrow><mi>d</mi></mrow><mrow><mn>10</mn></mrow></msub><mo>)</mo><mo>−</mo><msub><mrow><mi>ρ</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>|</mo><mo><</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>18</mn></mrow></msup></math></span> where <span><math><msub><mrow><mi>ρ</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>=</mo><mn>0.5</mn><mo>+</mo><mn>14.13</mn><mo>.</mo><mo>.</mo><mo>.</mo><mi>i</mi></math></span> is the first non-trivial zeta zero.</p><p>Also we define rational functions <span><math><msub><mrow><mi>R</mi></mrow><mrow><mi>N</mi><mo>,</mo><mi>n</mi></mrow></msub><mo>(</mo><mi>a</mi><mo>,</mo><msub><mrow><mi>d</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>,</mo><mspace></mspace><msub><mrow><mi>d</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mspace></m","PeriodicalId":54985,"journal":{"name":"Information and Computation","volume":"296 ","pages":"Article 105130"},"PeriodicalIF":1.0,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138685294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Fast synchronization of inhomogenous random automata","authors":"Balázs Gerencsér , Zsombor Várkonyi","doi":"10.1016/j.ic.2023.105129","DOIUrl":"10.1016/j.ic.2023.105129","url":null,"abstract":"<div><p>We examine the reset threshold of randomly generated deterministic automata. We present a simple proof that an automaton with a random mapping and two random permutation letters has a reset threshold of <span><math><mi>O</mi><mo>(</mo><msqrt><mrow><mi>n</mi><msup><mrow><mi>log</mi></mrow><mrow><mn>3</mn></mrow></msup><mo></mo><mi>n</mi></mrow></msqrt><mo>)</mo></math></span> with high probability, assuming only certain partial independence of the letters. Our observation is motivated by Nicaud (2019) providing a near-linear bound in the case of two random mapping letters, among multiple other results. The upper bound for the latter case has been recently improved by the breakthrough work of Chapuy and Perarnau (2023) to <span><math><mi>O</mi><mo>(</mo><msqrt><mrow><mi>n</mi></mrow></msqrt><mi>log</mi><mo></mo><mi>n</mi><mo>)</mo></math></span>.</p></div>","PeriodicalId":54985,"journal":{"name":"Information and Computation","volume":"296 ","pages":"Article 105129"},"PeriodicalIF":1.0,"publicationDate":"2023-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0890540123001323/pdfft?md5=038031fbeaebdbd099b82fc15b77abdd&pid=1-s2.0-S0890540123001323-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138493819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Complexity of the emptiness problem for graph-walking automata and for tilings with star subgraphs","authors":"Olga Martynova","doi":"10.1016/j.ic.2023.105127","DOIUrl":"https://doi.org/10.1016/j.ic.2023.105127","url":null,"abstract":"<div><p>This paper proves the decidability<span> of the emptiness problem for two models which recognize finite graphs: graph-walking automata<span>, and tilings of graphs by star subgraphs (star automata). Furthermore, it is proved that the non-emptiness problem for graph-walking automata (that is, whether a given automaton accepts at least one graph) is NEXP-complete. For star automata, which generalize nondeterministic tree automata to the case of graphs, it is proved that their non-emptiness problem is NP-complete.</span></span></p></div>","PeriodicalId":54985,"journal":{"name":"Information and Computation","volume":"296 ","pages":"Article 105127"},"PeriodicalIF":1.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138490275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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