It sounds like you might be misinterpreting the error. It looks to me like the site you're connecting to is self-signed or some other common problem. Just like the usual browser warning, you're easiest work around is to disable the checks.
You'll need to set
FALSE. This should disable the two main checks. They may not both be required, but this should at least get you going.
To be clear, this disables a feature designed to protect you. Only do this if you have verified the certificate and server by some other means.
More info on the PHP site: curl_setopt()