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Q: How best to handle the issue of security warnings for a website using certificates from its own CA (ie, selfsigned)?

I am some what torn on how to do this - I have a number of implementaiton thoughts.

On the one hand, I can redirect any incoming http request to an https landing page that explains the need for a one time exception or to install a "trusted" root cert and provide a button to continue to the requested page as https.

However, that seems a bit hokey. My other thought was just to have a security icon of some type on all the web pages, clicking on that would give more or less the same info and suggest the user in the future use https for connection.

There is no e-commerce involved so https is not critical in that sense. Though I personally would prefer to only offer secure connections, I now think it might be better to leave it up to the end user to decide. Either way, I felt it better to explain the dire unsafe certificate warning before any redirections.

Would like your thoughts on this, I'm sure some have gone through this already.

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  • I'm confused. If you put the explanation on the HTTPS landing page, you already have to have the certificate verified before the client sees the landing page explaining to add an exception.
    – cpast
    Commented Jan 28, 2015 at 3:58
  • explanation would be on http page.
    – TrustNoOne
    Commented Jan 28, 2015 at 16:47

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If this is a publicly accessible website, then use a certificate signed by a recognised CA. Downloading a random certificate distributed from the HTTP or the self signed HTTPS site is highly insecure. You are not only compromising the security of your website but also potentially the security of unsuspecting users who installed your root certificate.

Self-signed certificates are only useful in closed system where you have a secure secondary channel to distribute your certificate, where your users can validate with certainty that the certificate that they are about to install actually being to your site. The root certificate itself is a public key and is not considered a secret for HTTPS security, but if you distribute your root certificate through insecure channel, your users have no way to know for sure that the downloadable certificate in your unencrypted site actually belongs to the same site as the encrypted site or if their or your HTTP/self signed HTTPS connection might have already been MITM-ed, and the attacker has replaced your root certificate with the attacker's own root certificate. If the attacker managed to convince your user to install this spoofed root certificate, thinking it was from you, they can now MITM the HTTPS connection that your user thought is a secure connection to your site, without any browser warnings.

In short, use a recognised CA. Or distribute your certificate in such a way that your users can validate that it really is yours.

If you need HTTPS, there is really no reason not to get a certificate from a recognized CA. Some CAs, e.g. StartSSL, now provides basic validation certificates for free for personal sites (unless you are handling potentially illegal materials, which is another matter altogether).

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  • There are many reasons not to use a recognized CA. Cost being one and security being the other.
    – TrustNoOne
    Commented Jan 28, 2015 at 15:32
  • @TrustNoOne: as I said, you can get free SSL certificate from recognized CAs. If this is a publicly accessible site, using certificate from recognized CA is better security than self signed. If you're using self signed certificate without a secure side channel for distributing your certificate, you might as well just use no encryption rather than fooling your users into thinking that their connection to your site is secure.
    – Lie Ryan
    Commented Jan 28, 2015 at 15:55
  • @TrustNoOne: If this is a website restricted to a small number of users and you do have a secure second channel to deliver your certificate to them, then a self signed certificate is perfectly fine. The security of a self signed certificate is at most the ability of the distribution channel at attesting your identity. If your users already have your GPG or S/MIME that they can trust to be actually yours, you can digitally sign the certificate, this can also provide solid assurance that the certificate really belongs to you. Trust is a hard thing.
    – Lie Ryan
    Commented Jan 28, 2015 at 16:03
  • thank you for the last comment... I took to long in re-writing my earlier one in which I was going to ask your view of the least bad method of distributing the cert publicly
    – TrustNoOne
    Commented Jan 28, 2015 at 16:46
  • any thought on providing a signed hash of the cert using the dnssec keysigning or zone key?
    – TrustNoOne
    Commented Jan 29, 2015 at 17:22

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