IACR News item: 21 March 2025

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Hit enter to search with Google.</p> <form action="/search" method="GET"> <input id="searchboxMobile" name="q" type="search" class="form-control border searchBoxes" placeholder="Search IACR"/> </form> </div> </div> </nav> </div>  </div> <main id="iacrMain-contentBox" class="container px-md-4 py-3"> <section class="row"> <div class="col-12"> <h2> IACR News item: 21 March 2025 </h2> </div> </section> <div class="card newsItemBox" id="item-25341"> <div class="card-header pb-1"> <a id="item-url-25341" href="https://eprint.iacr.org/2025/525"> <h5 id="item-headline-25341"> Deniable Secret Sharing </h5> </a> </div> <div class="card-body"> <div class="d-flex"> <h6 class="card-title newsCardSubtitle mt-1 mr-auto" id="item-subheadline-25341"> Ran Canetti, Ivan Damgård, Sebastian Kolby, Divya Ravi, Sophia Yakoubov </h6> <img id="item-icon-25341" src="/img/icons/news/channel_10.svg" class="pl-1 newsCategoryIcon d-none d-md-block" title="ePrint Report channel" alt="ePrint Report" /> <span id="item-priority-25341" class="badge badge-dark priority5" title="ePrint Report channel">ePrint Report</span> </div> <div id="item-body-25341" class="card-text item-body"> We introduce deniable secret sharing (DSS), which, analogously to deniable encryption, enables shareholders to produce fake shares that are consistent with a target “fake message”, regardless of the original secret. In contrast to deniable encryption, in a DSS scheme an adversary sees multiple shares, some of which might be real, and some fake. This makes DSS a more difficult task, especially in situations where the fake shares need to be generated by individual shareholders, without coordination with other shareholders.<br><br> We define several desirable properties for DSS, and show both positive and negative results for each. The strongest property is fake hiding, which is a natural analogy of deniability for encryption: given a complete set of shares, an adversary cannot determine whether any shares are fake. We show a construction based on Shamir secret sharing that achieves fake hiding as long as (1) the fakers are qualified (number $t$ or more), and (2) the set of real shares which the adversary sees is unqualified. Next we show a construction based on indistinguishability obfuscation that relaxes condition (1) and achieves fake hiding even when the fakers are unqualified (as long as they comprise more than half of the shareholders). We also extend the first construction to provide the weaker property of faker anonymity for all thresholds. (Faker anonymity requires that given some real shares and some fake shares, an adversary should not be able to tell which are fake, even if it can tell that some fake shares are present.) All of these constructions require the fakers to coordinate in order to produce fake shares.<br><br> On the negative side, we first show that fake hiding is unachievable when the fakers are a minority, even if the fakers coordinate. Further, if the fakers do not coordinate, then even faker anonymity is unachievable as soon as $t < n$ (namely the reconstruction threshold is smaller than the number of parties). </div><span class="btn-link text-right expand-button body-expand">Expand</span> </div> </div> <div class="mt-4"> <p> Additional news items may be found on the <a href="/news/">IACR news page</a>. </p> </div> </main> <div id="pageFooter"> <footer class="container-fluid iacrMain-footer pt-4"> <div class="row px-4"> <div class="col-12 col-md-6 col-lg-3 mb-md-3"> <a href="/about/" class="h6 d-none d-md-block"> <strong>About</strong> </a> <p class="d-none d-md-block mt-2"> The <a href="/">International Association for Cryptologic Research (IACR)</a> is a non-profit scientific organization whose purpose is to further research in cryptology and related fields. <a href="/about/">Learn more...</a> </p> <div class="text-center"> <a href="//twitter.com/IACR_News" class="social" title="Twitter Feed"> <img src="/img/icons/twitter.svg" class="socialBtn" alt="Twitter logo"> </a> <a href="//youtube.com/TheIACR" class="social" title="YouTube Channel"> <img src="/img/icons/youtube.svg" class="socialBtn" alt="YouTube logo"> </a> <a href="//www.facebook.com/theiacr/" class="social" title="Facebook Page"> <img src="/img/icons/facebook.svg" class="socialBtn" alt="Facebook logo"> </a> <a href="https://weibo.com/iacr" class="social" title="Weibo"> <img src="/img/icons/weibo.svg" class="socialBtn" alt="Weibo logo"> </a> </div> </div> <div class="col-12 col-md-6 col-lg-3"> <a href="/meetings/" class="h6"> <strong>Events</strong> </a> <ul class="list-unstyled"> <li> <a href="/meetings/asiacrypt/">Asiacrypt</a>  •  <a href="/meetings/crypto/">Crypto</a>  •  <a href="/meetings/eurocrypt/">Eurocrypt</a> </li> <li> <a href="/meetings/ches/" title="Cryptographic Hardware and Embedded Systems">CHES</a>  •  <a href="/meetings/fse/" title="Fast Software Encryption">FSE</a>  •  <a href="/meetings/pkc/" title="Public Key Cryptography">PKC</a>  •  <a href="/meetings/tcc/" title="Theory of Cryptography Conference">TCC</a> </li> <li> <a href="//rwc.iacr.org/"> Real World Crypto </a> </li> <li> <a href="/schools/"> Schools </a> </li> <li> <a href="/events/"> Calendar of events </a> </li> </ul> </div> <div class="col-12 col-md-6 col-lg-3"> <a href="/publications/" class="h6"> <strong>Publications</strong> </a> <ul class="list-unstyled"> <li> <a href="/publications/access.php"> Access to Publications </a> </li> <li> <a href="/jofc/"> Journal of Cryptology </a> </li> <li> <a href="/transactions/tosc/"> Trans. on Symmetric Cryptology </a> </li> <li> <a href="https://tches.iacr.org/"> Trans. on CHES </a> </li> <li> <a href="https://cic.iacr.org/"> Communications in Cryptology </a> </li> <li> <a href="//eprint.iacr.org/"> Cryptology ePrint Archive </a> </li> <li> <a href="/cryptodb/"> Publication database </a> </li> </ul> </div> <div class="col-12 col-md-6 col-lg-3"> <a href="/services/" class="h6"> <strong>Services</strong> </a> <ul class="list-unstyled"> <li> <a href="/news"> News </a> </li> <li> <a href="/awards/"> Awards </a> </li> <li> <a href="/jobs/"> Jobs </a> </li> <li> <a href="https://register.iacr.org/membership/members/">Update your information</a> </li> <li> <a href="/membership.php">How to join</a> </li> <li class="d-block d-md-none"> <a href="/about/"> About the IACR </a> </li> </ul> </div> </div> <div class="row"> <div class="col-12 iacrMain-bottomOfFooter text-center py-2 mt-3"> <span class="align-middle"> <a href="/copyright.html">Copyright © <span id="thisYear"></span> <script>document.getElementById("thisYear").innerHTML = new Date().getFullYear();</script> <span class="d-none d-md-inline">by the </span><span class="d-md-none">IACR</span><span class="d-none d-md-inline">International Association for Cryptologic Research</span></a> <span class="d-none d-md-inline">• </span><br class="d-md-none"> <a href="/privacy.html">Privacy Policy</a> </span> </div> </div> </footer>  </div> <script src="https://iacr.org/libs/js/jquery/3.3.1/jquery.min.js"></script> <script src="https://iacr.org/libs/css/bootstrap/dist/js/bootstrap.bundle.min.js"></script> <script src="https://iacr.org/libs/js/easy-autocomplete/jquery.easy-autocomplete.js"></script>  <script src="/js/search.js"></script> </body> </html>

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IACR News item: 21 March 2025