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60 61</head> 62 63 <body class="theme-base-0b layout-reverse"> 64 <aside class="sidebar"> 65 <div class="container"> 66 <div class="sidebar-about"> 67 <img src='/nils.jpg' style='border-radius: 50%'> 68 <a href="https://nilsfleischhacker.de/"><h1>Nils Fleischhacker</h1></a> 69 <p class="lead"> 70 Cryptographer working in applied and theoretical cryptography. Currently a Visiting Researcher at Flashbots. 71 </p> 72 </div> 73 </div> 74 <div class="container sidebar-sticky"> 75 <nav> 76 <div class="sidebar-nav"> 77 <a href="https://scholar.google.de/citations?user=cJpkmxsAAAAJ&hl=en&oi=ao"> <i class="fa-brands fa-google-scholar"></i> </a><a href="https://dblp.org/pid/78/10700.html"> <svg xmlns="http://www.w3.org/2000/svg" fill="#fff" enable-background="new 0 0 24 24" viewBox="0 0 24 24" width="20" height="20" id="dblp" style="margin-bottom: -4; margin-left: -1;"><path d="M2.779,9.45l2.429,9.16c0,0,0.159,0.59,0.714,0.33l7.407-3.48c0,0,0.516-0.24,0.417-0.79l-0.01-0.06l-1.12-4.22L11.96,7.94l-0.664-2.49V5.41c0,0-0.159-0.59-0.833-1l-6.891-4.27c0,0-0.674-0.41-0.516,0.17l1.973,7.42L3.175,8.6C3.175,8.6,2.62,8.86,2.779,9.45z"></path> <path d="M21.221,14.58L18.792,5.42c0,0-0.149-0.59-0.714-0.33l-5.553,2.6l0.853,3.2l1.081,4.08l0.01,0.06c0.05,0.47-0.407,0.79-0.407,0.79l-1.864,0.87l0.496,1.89l0.04,0.1c0.069,0.17,0.278,0.6,0.803,0.91l6.891,4.27c0,0,0.674,0.41,0.516-0.17l-1.963-7.4l1.844-0.86C20.825,15.43,21.38,15.17,21.221,14.58z"></path></svg> </a><a href="https://orcid.org/0000-0002-2770-5444"> <i class="fa-brands fa-orcid"></i> </a><a href="https://github.com/nilsfleischhacker/"> <i class="fa-brands fa-github"></i> </a><a href="https://bsky.app/profile/cryptomaeher.bsky.social"> <i class="fa-brands fa-bluesky"></i> </a><a href="https://www.linkedin.com/in/nils-fleischhacker/"> <i class="fa-brands fa-linkedin"></i> </a><a href="mailto:[email protected]"> <i class="fa-solid fa-at"></i> </a> 78 </div> 79 </nav> 80 </div> 81</aside> 82 83 <main class="content container"> 84 <div class="post"> 85 <h1>Pseudorandom Signatures</h1> 86 <span class="pub-authors" itemprop="author"> 87 88 Nils Fleischhacker, Felix Günther, Franziskus Kiefer, Mark Manulis, Bertram Poettering 89 90 </span> 91 <h3>Abstract</h3> 92 <div class="pub-abstract" itemprop="text">We develop a three-level hierarchy of privacy notions for (unforgeable) digital signature schemes. We first prove mutual independence of existing notions of anonymity and confidentiality, and then show that these are implied by higher privacy goals. The top notion in our hierarchy is <em>pseudorandomness</em>: signatures with this property hide the entire information about the signing process and cannot be recognized as signatures when transmitted over a public network. This implies very strong unlinkability guarantees across different signers and even different signing algorithms, and gives rise to new forms of private public-key authentication.<br> 93We show that one way towards pseudorandom signatures leads over our mid-level notion, called <em>indistinguishability</em>: such signatures can be simulated using only the public parameters of the scheme. As we reveal, indistinguishable signatures exist in different cryptographic settings (e.g. based on RSA, discrete logarithms, pairings) and can be efficiently lifted to pseudorandomness deploying general transformations using appropriate encoding techniques. We also examine a more direct way for obtaining pseudorandomness for any unforgeable signature scheme. All our transformations work in the standard model. We keep public verifiability of signatures in the setting of system-wide known public keys. Some results even hold if signing keys are disclosed to the adversary â given that signed messages have high entropy.</div><br> 94</div> 95 96 </main> 97 </body> 98</html>
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