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Comment by rodgerd | Hacker News Reader

I'd trusts self-signed certs ahead of most CAs, frankly.

That doesn't make any sense.... even if you don't trust a CA at all, it is impossible for a self-signed cert to be MORE trustworthy, since it provides absolutely ZERO authentication. It could be created by anyone at all, including on the fly by a MITM.

Trusting myself with out-of-band verification rather than trusting a third-party to do out-of-band verification is more trustworthy.

If you do not trust yourself to do it, why do you trust that the third-party would?

Yes, if you use a self signed cert and out-of-band verification, then yes it would probably be more trustworthy than a third-party verified cert (like a CA).

I don't think that is what the parent was saying, however, in saying he would trust a self-signed cert. I don't think he meant "Call up the website host and ask for them to verify their public key"

Maybe he is saying by removing trusted root certificates he will trade the possibility of receiving a fraudulent certificate the first time he uses a site for the possibility of not being warned if a certificate changes because the trusted roots are compromised. If he needs to worry about state actors there is an argument to be made for this trade-off, but really if he was worried about that he would be delivering certificates out of band and not visiting any unknown websites on the machine he needed that level of security on. (Maybe justifiable against mass surveillance where you're a general target rather than a specific one).

Yes, verifying certs out-of-band is most likely more secure than a CA. I was not counting that in the self-signed cert vs CA signed cert comparison, since that is not what most people mean when they talk about a self-signed cert.

You ignored my first point. You can trust the self signed certificate to be used by the same entity(A or C) after the first connection, admittedly you may have been MITM (by C) for that first time(and renewal times) and because of that you may be screwed. Alternatively if you are trusting other entities(B) to verify the certificate of A while B are not trustworthy then after that first communication (even if that first communication was legitimate) another entity (C) can pretend to be A and so long as B verifies C then you are in trouble. I am pointing out that they are different risks and I agree that in nearly all use cases it is better to use verified certificates than self-signed for general internet use, that doesn't mean that there isn't a reason to do otherwise though.

There are extensions to warn you about certificate changes even if the new is signed by a CA, so that's a terrible reason.

Ah, yes, certificate patrol[0]. However, your argument, I think, is not valid. Sure, it's technically possible for him to know if any cert changes, but in reality very few people are going to install the extension and those that do might not even notice the message because it notifies the user so frequently (fully desensitizing them I imagine).

I don't think that his choice not to install an extension invalidates his argument.

[0]: https://addons.mozilla.org/en-us/firefox/addon/certificate-p...

very few people are going to install the extension

My argument is, pinning certs is a bad reason for removing the root certs from the browser, since you can pin them without breaking the CA chains.

I'm not sure how does that work as a counter-argument; We're discussing a decision of a particular person, not some broad policy. How is the number of people who install the extension relevant?

those that do might not even notice the message because it notifies the user so frequently (fully desensitizing them I imagine)

So does the browser, if you remove the root CA certs.

That's only true if you're not verifying the identify of the presented cert - how do you suppose client/server certificates work? For example, along the lines of what every VPN system in the world uses? VeriSign isn't involved in the transaction between my company laptops and the ASA in my datacenter.

Besides, having the third party CA signature in this day and age doesn't tell me much other than the person presenting the cert coughed up whatever protection money the particular face of the PKI protection racket demands, and ostensibly the CA did some level of verification (could be more, could be less, I honestly do not know or have time to find out) as to the "identity" of the person who's info is on the CSR.

Really, for your own uses, you're better off self signing with your own CA, noting down the identifying information of the cert at generation time, and then installing that cert as trusted either ahead of time, or hitting it from the third party and double checking the information matches up.

TOFU: don't most browsers tell you if you've been to the site before, and whether the cert has changed since your last visit? I seem to recall that at one time Firefox could be configured to not even complain when it saw a self-signed cert it recognized?

No. That is a capability provided by an extension called CertPatrol, at least in the Firefox ecosystem.

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