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--></style></head><body lang=EN-US link="#0563C1" vlink="#954F72" style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal><span style='font-size:12.0pt'>TLDR; <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt'>Need to create a CSR for a key pair whose algorithm does not allow signing (either because it’s something like Kyber, or because restriction enforced by HSM). How to do it?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt'>There are several use cases that require certifying long-term asymmetric keys that are only capable of encryption/decryption – but not signing/verification. That could be either because the algorithm itself does not do signing, or because the private key is generated and kept in a secure hardware that enforces usage restriction.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt'>CSR is supposed to be signed by the corresponding private key to prove possession. Obviously, it cannot be done with a key such as described above. How is this problem addressed in the real world? With AuthKEM and KEMTLS, how would these protocols get their certificates?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt'>Thanks!<o:p></o:p></span></p><div><div><p class=MsoNormal><span style='color:black'>--</span><span style='font-size:12.0pt;color:black'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Andale Mono";color:black'>V/R,</span><span style='font-size:12.0pt;color:black'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Andale Mono";color:black'>Uri Blumenthal Voice: (781) 981-1638 </span><span style='font-size:12.0pt;color:black'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Andale Mono";color:black'>Secure Resilient Systems and Technologies Cell: (339) 223-5363</span><span style='font-size:12.0pt;color:black'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Andale Mono";color:black'>MIT Lincoln Laboratory </span><span style='font-size:12.0pt;color:black'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Andale Mono";color:black'>244 Wood Street, Lexington, MA 02420-9108 </span><span style='font-size:12.0pt;color:black'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Andale Mono";color:black'> </span><span style='font-size:12.0pt;color:black'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Andale Mono";color:black'>Web: <a href="https://www.ll.mit.edu/biographies/uri-blumenthal" title="https://www.ll.mit.edu/biographies/uri-blumenthal"><span style='color:#713C56'>https://www.ll.mit.edu/biographies/uri-blumenthal</span></a></span><span style='font-size:12.0pt;color:black'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Andale Mono";color:black'>Root CA: <a href="https://www.ll.mit.edu/llrca2.pem" title="https://www.ll.mit.edu/llrca2.pem"><span style='color:#713C56'>https://www.ll.mit.edu/llrca2.pem</span></a></span><span style='font-size:12.0pt;color:black'><o:p></o:p></span></p><p class=MsoNormal><span style='color:black'> </span><span style='font-size:12.0pt;color:black'><o:p></o:p></span></p><p class=MsoNormal><i><span style='color:black'>There are two ways to design a system. One is to make it so simple there are obviously no deficiencies.</span></i><span style='font-size:12.0pt;color:black'><o:p></o:p></span></p><p class=MsoNormal><i><span style='color:black'>The other is to make it so complex there are no obvious deficiencies.</span></i><span style='font-size:12.0pt;color:black'><o:p></o:p></span></p><p class=MsoNormal><i><span style='color:black'> - C. A. R. Hoare</span></i><span style='font-size:12.0pt;color:black'><o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p></div></body></html>