A method is provided for adding intended meaning to digital signatures. A message, being base content, is received to be signed. Assertions, ontologies, and description of a reasoner are adjoined to the message. Ontologies are a formal specification of vocabulary and rules used to state the assertions. The reasoner validates the assertions against the corresponding ontologies. A compound message is formed including the message, the assertions, the ontologies, and the reasoner. The compound message is signed using a cryptographic digital signature, where the assertions indicate an intended meaning of the digital signature. During verification of semantic signatures, a digital signature is received for a compound message, where the compound message includes assertions, ontologies, and reasoner. The digital signature is verified, and the compound message structure is checked for semantic signature conformance. In response to proper verification, the reasoner is utilized to verify a conformance of the assertions to the ontologies.