\begin{kaupaper}[ author={% \textbf{Rasmus Dahlberg}, Paul Syverson, Linus Nordberg, and Matthew Finkel }, title={% Sauteed Onions: Transparent Associations from Domain Names to Onion Addresses }, reference={% WPES (2022) }, summary={% Many prominent websites are also hosted as Tor onion services. Onion services are identified by their public keys and subject to onion routing, thus offering self-authenticated connections and censorship resistance. However, the non-mnemonic names are a limitation due to being hard to discover and remember. We explore how certificates with onion addresses may improve the status quo by proposing sauteed onions, \emph{transparent associations from domain names to onion addresses} with the help of Certificate Transparency logs. The idea is to extend a website's regular certificate with an associated onion address. This makes it possible to offer certificate-based onion location that is no less targeted than the HTTPS connection facilitating the discovery, as well as name-to-onion search engines that use the append-only logs for verifiable population of their databases. The achieved goals are consistency of available onion associations, improved third-party discovery of onion associations, and forward censorship-resistance. To be discovered, sites must opt-in by obtaining a sauteed onion certificate. Our prototypes for certificate-based onion location and third-party search engines use an existing backward-compatible format. We discuss this trade-off and note that a certificate extension may be used in the future. }, participation={\vspace{-.25cm} Paul, Linus, and I had the initial idea of exploring how onion addresses fit into Certificate Transparency. Paul and I did most of the writing. I implemented our monitor, Linus our search engine, Matt our web extension. }, label={ paper:sauteed }, ] \maketitle \begin{abstract} \input{src/sauteed/src/abstract} \end{abstract} \input{src/sauteed/src/intro} \input{src/sauteed/src/preliminaries} \input{src/sauteed/src/sauteed} \input{src/sauteed/src/related} \input{src/sauteed/src/conc} \input{src/sauteed/src/acks} \bibliographystyle{plain} \bibliography{src/sauteed/src/refs} \begin{appendices} \input{src/sauteed/src/appendix} \end{appendices} \end{kaupaper}