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nickwitha_k ,

Not pictured: Using a CA to properly administer certs because self-signed certs are not secure.

Fal ,
@Fal@yiffit.net avatar

They’re more secure than CA certs

nickwitha_k ,

Could you explain your statement further?

Fal ,
@Fal@yiffit.net avatar

Basically with self signed certs, you control the ENTIRE trust chain. When you use existing CAs, any bad actor in any of those CAs can generate certs that you would end up trusting. So it’s less secure because you have to trust a lot more people.

nickwitha_k ,

And if you’re not using a trusted CA, you are unable to protect against MitM and other forgery attacks, as well as needing to rely upon a mechanism like TOFU in order to avoid auth fatigue and other human error, which is not great.

Fal ,
@Fal@yiffit.net avatar

you are unable to protect against MitM and other forgery attacks

Uhh, using a self signed cert doesn’t mean you just accept any old cert… Not every cert is designed for serving content to a browser. You do SSL mutual auth between services using self signed certs

nickwitha_k ,

You do SSL mutual auth between services using self signed certs

If you do, you remove the ability to prove that a service is what it claims to be as this requires accepting its provided cert - that is, authenticate it. You have to trust somewhere, even in a “zero trust” environment. Using self-signed certs for services to communicate means that you have to either have manual involvement every time a service comes up or accept the authenticity of a self-signed cert automatically. Either would be a compromise in security over use of a private CA, not an improvement.

Again, that works if your only concern is data across the pipes being encrypted during transmission but, it removes nearly all of the other additional security provided by PKI and increases your threat surface. It can be acceptable in some cases, like dev envs or as temporary measures but, with the constant increase in malicious traffic and activity, we’ve got to aim for better.

Fal ,
@Fal@yiffit.net avatar

Oh. I’m absolutely including a private CA as part of self signed cert. That’s probably my misuse of the term

nickwitha_k ,

Oh! Then you are doing it right. That was basically my entire objection - having A chain of trust is necessary to effectively and securely use certs because you have a mechanism to validate, rather than trust the cert that is presented as authentic. :)

slazer2au ,

How are they not secure? You are still doing TLS to the service, maybe they have weak keys but it is still a form of secure connection.

nickwitha_k ,

Certs do more than encryption in transit. They are also used for protection against MitM and authentication. Self-signing removes the ability to verify a cert’s authenticity.

Daqu ,

That’s bullshit. You are the one who issued the cert. You can add it to your list of trusted certificates. You just have to check that this is the right certificate.

Your man in the middle scare comes from users who ignore cert warnings and continue without checking anything.

nickwitha_k ,

That’s bullshit.

Nope. That’s the basics of PKI and scalable, secure, low-trust environments.

You are the one who issued the cert. You can add it to your list of trusted certificates. You just have to check that this is the right certificate.

You can indeed do these things. But, are you and your users going to verify every cert for every request and response? That’s a lot of unnecessary cognitive load and tedium, both of which are known to compromise judgement. Are you going to automate it? Ok then how are you going to verify the authenticity of a given cert?

Your man in the middle scare comes from users who ignore cert warnings and continue without checking anything.

Humans are not rational actors. Does everyone read the entire EULA? Not even close.

The problem with your statement, and why it is fallacious, is that you are not accounting for humans besides yourself. I’d even argue that you should also take your human nature into account because we all make mistakes.

Robust security postures do not require everyone to act perfectly but accept and plan for the fact that we’re fallible. That is why chains and webs of trust were created, so that humans and automated services can take an approach of deference towards a less mutable “expert” on whether a claim of authenticity is trustworthy - giving them the capability and responsibility of deciding this for themselves introduces unnecessary targets for exploits.

Daqu ,

Your man in the middle argument is invalid, no matter how much you write. Just trust youur self signed certs and you users see no difference. That’s even more secure than blindly trusting the idiots from verisign.

Don’t act so smug.

nickwitha_k ,

Your man in the middle argument is invalid, no matter how much you write.

It really isn’t and it’s a significant part of why PKI exists in the first place. I’ve been doing this stuff professionally for over a decade and am very familiar with ISO27001, SOC2, and CIS standards, as well as generally just finding that a healthy dose of paranoia in computing keeps things more secure. Understanding how and why PKI works and is architected as it is is something that I recommend that everyone involved in technology explore.

Just trust youur self signed certs and you users see no difference.

This is problematic if a service needs to be redeployed, the cert expires, or becomes compromised, leaking its keys. In the former two scenarios, the new cert needs to be added on all of your end users’ machines. If you have just a few users, sure, that’s easy enough but, tedious and unnecessary. If it is a case of the latter, you now need to revoke the cert on all systems that have trusted it and deploy a new one. Again, tedious and prone to human error. Plus, you have to hope that you detect this quickly, otherwise a malicious host can harvest a lot of potentially-sensitive information, a situation easily prevented with a trusted CA.

That’s even more secure than blindly trusting the idiots from verisign.

I’m not suggesting that a public CA is the best choice for everyone or every situation. For internal use, a well-managed private CA or LE is probably a better choice, purely from a cost perspective.

I’d also like to understand why you are so hostile towards Verisign and feel better qualified in cert management. Were you or someone close to you caught up in their 2010 breach?

Don’t act so smug.

Not sure where this hostility is coming from. I am primarily explaining how these statements are not in line with intended use of security technologies and best practices. If you don’t like currently accepted security best practices, that’s absolutely your prerogative.

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