[Ach] Publish own CA certificate. Loss of security?

[ianG]

On 19/01/14 13:29 PM, Torge Riedel wrote:
> Hi,
> 
> just a question I was just faced with:
> 
> For my own server I created my own CA certificate with which I signed
> new certificates for all of my services. My CA certificate is protected
> by a key.

The public key is in the certificate, unencrypted.  The private key is
kept private, and is typically protected by a secret key (encrypted).

> Is it a loss of security if I publish the CA certificate by -
> let's say - a web site so visitors of my https-protected web site can
> import it to their browser's cert list?


That is the theory and the intent:  you publish the public key, and then
your users (or their browsers) can rely on it.

> As I understood no one else can use my CA certificate to sign own
> certificates without knowing the key. Is this right?


Correct.

However, the security relies on some assumptions:  Primarily that you
created your key well.  If you have not used a good RNG then it might be
that someone can crunch it.  This was the problem with the Debian and
Android attacks -- the RNGs failed, and crunches and hacks followed.
It's also been shown tnat some non-trivial proportion of keys on the net
are the same key or can be crunched if you know what the platform is,
because the RNG was weak.


iang