A system for providing authenticity, integrity, and non-repudiation to advertising technology. At least one processor receives an ad request for an ad impression available for sale. The ad request includes attributes associated with the ad impression and a cryptographic proof that provides non-repudiation and data integrity of the ad request. The ad request is authenticated by querying a blockchain. The processor accesses a database of second parties seeking to purchase ads online. The database stores attributes associated with each second party, matches the ad request with a selected second party based on the attributes associated with each second party in the database and the attributes associated with the ad impression of the ad request. The processor transmits to the first party a message having an ad and a cryptographic proof of the message, so as to fill the ad impression with the ad for the selected second party.