This property can contain certificates used to verify message signature.
Use this property to specify
certificates which should be used to verify signed messages.
You may leave this property empty if you are verifying the public-key signature (i.e. if SignatureType is mstPublicKey). But, you must assign it if the SignatureType is mstMAC. Moreover, for mstMAC signatures the certificates stored in specified certificate storage must contain corresponding private keys.