How do you know if a CA is trusted?

Question

I have a client who wants their app code signed, so we pointed them to a few well known, well trusted CAs (Verisign, Thawt, etc), then they came back with InstantSSL (because it was only 180/yr as opposed to 500/yr).

How do I know that InstantSSL will be trusted on a customer of this application's computer?

Answer 1

InstantSSL certificates has Comodo as the root authority. It is installed and trusted by default on all recent Windows versions. (And it is on the current list)

Answer 2

Wikipedia to the rescue ! :-)