1. A method on a computer for adding intended meaning to digital signatures comprising: forming a compound message on the computer which comprises: receiving a message, being base content, to be signed; adjoining assertions to the message; adjoining ontologies to the message, wherein the ontologies are a formal specification of vocabulary and rules used to state the assertions; adjoining a description of a reasoner to the message, wherein the reasoner is configured to validates the assertions against the corresponding ontologies, the reasoner is configured to validate a syntactic conformance of the assertions to the rules of the ontologies, and the reasoner is configured to determine subsumption relationships between terms in the assertion including when one term denotes entities more general than other entities; and adjoining world beliefs to the message, wherein the world beliefs provide background knowledge to the reasoner; wherein forming the compound message on the computer comprises combining each of the message, the assertions, the ontologies, the description of the reasoner, and the world beliefs into a single semantic structure to be signed with a key as the compound message; and signing the compound message being the single semantic structure using the key such that the message, the assertions, the ontologies, the description, and the world beliefs are included within the compound message signed by the key, wherein the assertions indicate an intended meaning of the key when verified.