2023-06-09T12:17:06Z https://yabu.me Corné Plooy [ARCHIVE] https://yabu.me/npub1ly5vrg5ylhdkxrkj824jhlnfsy2z8fvlg8wcc0jqc4aezma6majsycdx6n https://yabu.me/nevent1qqsprr8plr7dzhtrrs0ccth3fh8mdsf40lgguew5e8a0wk6tl5zr38gzyruj3sdzsn7akccw6ga2k2l7dxq3gga9naqamrp7grzhhyt0ht0k2r0crgr In reply to <a href='/nevent1qqsgv4dnr8jsvuf478wpunm29h4s4rvwtexqnd0lenlfvxeu4qlynss5l0e5s'>nevent1q…0e5s</a><br/>_________________________<br/><br/>📅 Original date posted:2018-11-29<br/>📝 Original message:<br/>Hi,<br/><br/><br/>Is there a reason why we have HMACs in Sphinx? What could go wrong if we<br/>didn&#39;t?<br/><br/>A receiving node doesn&#39;t know anyway what the origin node is; I don&#39;t<br/>see any attack mode where an attacker wouldn&#39;t be able to generate a<br/>valid HMAC.<br/><br/>A receiving node only knows which peer sent it a Sphinx packet;<br/>verification that this peer really sent this Sphinx packet is (I think)<br/>already done on a lower protocol layer.<br/><br/><br/>AFAICS, The only real use case of the HMAC value is the special case of<br/>a 0-valued HMAC, indicating the end of the route. But that&#39;s just silly:<br/>it&#39;s essentially a boolean, not any kind of cryptographic verification.<br/><br/><br/>CJP 2023-06-09T12:53:14Z