3 ms·

iirc that's already possible, it's how letsencrypt started out without its own root widely distributed by having its intermediate certificates cross-signed with

• tialaramex 6y ago
  No, your parent is describing sending two leaf certificates, which won't work. You can send multiple intermediates, and some clients are intelligent enough to ignore the ones they don't trust. But unfortunately not all clients get this right, and the ones least likely to do so are also the older ones that likely will cease working when Identrust's DST Root CA X3 expires. A smart modern client (e.g. most current web browsers) will just use anything else you send as a hint that can help it find a way to trust the leaf certificate. You can send irrelevant garbage and it won't count against you, but because other dumber clients exist, you are recommended not to send anything that doesn't form a logical chain of certificates back to a trusted root. Old versions of OpenSSL for example provide a trust decision framework that assumes any chain you show it is the only valid chain, if that chain is nonsense or untrusted, it gives up and fails immediately, even if it would be obvious to a human shown the same certificates that there's a simple and correct trust path. This is harder than it might seem because it's a graph problem and the Web PKI graph contains multiple cycles, a naive algorithm may spin uselessly forever or miss "obvious" answers.
  • lxgr 6y ago
    Very interesting! Out of curiosity, how could there be cycles in the graph?