Weakening TLS protection, South Korean style
I think the whole design of PKI is bad. Instead on trusting a handful CAs that have to charge for or severely limit access to their signing servers, PKI could be based on the DNS hierarchy. CA type certificates do have an extension for specifying at which DNS level and below they are valid, so the root DNS operators would have the root cert and would only issue signatures for CA certs to TLDs that are limited to those TLDs only. A TLD administrator would then sign CA certs for second level domains that are time limited to domain validity and have their CA limited to this SLD and below.<p>An owner of an SLD would automatically get a CA cert and wouldn't need to depend on third party issuers (and their OCSP servers to which data leaks), complicated ACME protocols, ...<p>A bank in question could then sign certs for each user and point domains user58284u2874localhost.bank.example to 127.0.0.1. Even better, the bank would be much more secure because there would be no other CA that could sign certs for it's domain, apart from THE SINGLE root CA and it's TLD CA.<p>This entire process of basing on DNS as a security chain already exists in form of DANE/TLSA, which is IMO an even simpler protocol than CA and cert chains. With DANE, TLSA records containing TLS public keys (or cert hashes), trusted on a specific domain, are published in DNS zones, which must be signed by DNSSEC. That way, TLS certificates don't even need to be signed by a CA. No browser currently implements DANE however, it's major users are currently mailservers.