Just a quickie...
Windows 8 windows update error 80096002 is a certification error - here is the code header:
// MessageId: TRUST_E_NO_SIGNER_CERT
// The certificate for the signer of the message is invalid or not found.
#define TRUST_E_NO_SIGNER_CERT _HRESULT_TYPEDEF_(0x80096002L)
However, this can also be generated when you are trying to do updates from a WSUS server and meant to get them from the internet, check the little blue text that says:
"Check online for updates from Windows updates"