Digital Certificate Security

Question

I've been google'ing about the security of the digital certificates and I wasn't able to find an answer to my question: is it secure to use one private key for the signing of multiple certificates? Thanks.

Answer 1

That is exactly what all Certificate Authorities do. SSL servers do the same all the time, and individuals that sign multiple documents with one certificate's private key do this. So of course this is secure.

Answer 2

The digital certificate signs the public key of the entity with the private key of a trusted third party. There is a chain of trust which has to be trusted at some point at which verification can be done.