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I don't understand the https security model attempted upon me by The OpenBSD Journal (undeadly.org).

Instead of using self-signed certificates for https like they did in the past, they for a while have had 6-month certificates signed by Root CA, which they do appear to change at least somewhat promptly. I guess that cacert.org has some kind of a 6-month limit on certificates?

As an undeadly.org user, am I supposed to blindly accept a new cert every 6 months?

Import CA Cert Signing Authority Root CA from http://www.cacert.org into my browser?

Ask the admins to go self-signed route instead, making a cert for maybe 2 to 10 years, which I'd only have to accept once?

P.S. It looks like cacert.org used to be included in OpenBSD's cert.pem and ports/security/nss at one point, but was henceforth removed on 2014/04/09 and 2014/04/29, respectively, following a redistribution licence incompatibility review.

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  • you could inspect the new cert when they issue it
    – schroeder ♦
    Apr 16, 2015 at 17:30
  • @schroeder, basically, every single time i am to make a new comment?
    – cnst
    Apr 16, 2015 at 17:35
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    Do you trust CAcert to not issue any illegitimate certificates for any site? If so, importing them as a trust root is exactly what you're supposed to do.
    – cpast
    Apr 16, 2015 at 17:40
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    @cnst Set-it-and-forget-it is actually a bad approach to certificates. Certificate revocation doesn't work that well; lots of clients either don't support revocation, or can be kept from checking revocation status by a MitM (so they just accept the cert). That means that if your private key is compromised, even if you know it's compromised, an attacker can get a lot of devices to trust the certificate until its expiration date.
    – cpast
    Apr 16, 2015 at 18:34
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    @cnst Generally, CA root private keys are much more securely kept than server authentication private keys. See this answer for details on how CA certs tend to be kept. I'm not sure if CAcert follows those practices, but in general a web server is less trustworthy than a proper CA setup (which doesn't need to expose nearly as much).
    – cpast
    Apr 16, 2015 at 20:20

2 Answers 2

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The PKI model works on the trust you can give to the initial third party. Namely, the root CA. If you trust the root CA, you should import their root certificate, so that any certificate they issue (sign) will be automatically accepted by your system.

If you do not trust the CA, well there is nothing more you can do. So why would you trust CAcert.org ? Well, you can take a look at their Web of Trust system, where you can get assurance about certificates (I won't go in details here). Another question is: why would you trust the other root certificates already on your machine more than cacert?

Then to the question of is it more reliable than a self-signed one? Well, you could argue that the process involves at least two people, the CA and the website. Unless they are accomplice, it's usually better than self-signed only. Of course, all is based on the trust you can grant the CA.

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Trusting a CA means that you trust the CA for all certificates issued by this CA. But because all CAs are treated the same by the browser (except for EV certificates) any CA could create a certificate for any site. This means it is enough if a single trusted CA is not as trustworthy as needed and this kind of trust problems happened several times in the past.

And because there are already problems with the CAs currently trusted by most browsers you might think twice before importing a CA as trusted which tried but failed to be added as trusted to browsers and operating systems.

On the other hand, if you just accept any self-signed certificate without properly verifying it then you are vulnerable too. Proper verification might be done by getting the certificates fingerprint from a trusted source via a tamperproof transport and then comparing it to the fingerprint shown by the browser. If you do the verification like this then a self-signed certificate can be actually more trustworthy then a certificate issued by any of the trusted CAs in the browser.

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