Not to take away from that, it's also very easy to get wrong as well.
- Not doing CA verification check[1]
- No alerts/monitoring of new certificates used by the IDP
- No verification on certificate-transparency of new certificates used by the IDP
- No online CRL checking
If you do not do these things, then your application-on-HTTP is insecure. Remember that it's very easy to get a new certificate if you can break IP either by MITMing the server or by BGP takeover of some space near the CA. Both of these things have happened.
If there's a way you can detect incorrect implementations, then blacklist them. For example, I use OAuth2 in my own systems, but I require clients retry (by randomly failing during onboarding) and implement fuzzing whereby the client_secret is invalidated if they accept an invalid certificate.
[1]: http://web.archive.org/web/20120317165131/http://forum.devel...
Specifically they are Google's Chrome (Android), Microsoft's IE/Edge (Windows), Apple's Safari (iOS/ macOS) leaving only Mozilla's Firefox (standing in for the Free Unixes). If there's a fifth it's Oracle, as custodians of Java.
A tremendous weight ends up resting on the shoulders of these vendors, all of them based on the US West Coast, and it's not as though this a power _seized_ by them, it's more something everybody else shirked.
SFTP/FTPS, SSH, SMTPS, etc.
* SFTP/FTPS (SSH)
* SSH (SSH)
* SMTPS (SSL, TLS)
You know that thing that gives security practitioners a bad reputation with engineers?
You're doing it.
As opposed to this, why not something more like "it's not uncommon for these two to be confused, but FTPS is FTP over TLS and isn't interchangeable with SFTP"?
I guess it is IETFs job to standardize stuff so that is what they do -- for a hammer everything is a nail, right?
P.S. I skimmed it, so perhaps it is worth a read, but nothing caught my eye really.