IOHK | WHY WE ARE BUILDING CARDANO | 06/28/2017    For Cardano, we first have to establish what would a legacy bridge even entail? What systems, standards, entities and protocols should we target to ensure there is a reasonable certainty of interoperability? Can these bridges be federated or decentralized? Or like exchanges will they become central points of failure for hackers, malicious owners or overzealous regulators? There are three concerns that have to be addressed. First, the representation of information and belief in its accuracy. Second, representation of value and its associated ownership. Third, representation of entities and, a particular user’s alongside the aggregate level of trust in such entities. To be useful, information and value need to freely flow between the legacy financial world and Cardano. Then outcomes need to be established and recorded to build reputation and grounds for recourse. Yet such things are mostly scoped in nature to the actors involved. To encode them on a blockchain would make them global and permanent. Furthermore, value cannot always freely flow in the legacy world. Embargos, sanctions, capital controls and judicial action could freeze assets. To be interoperable, one cannot create an always open escape valve for value to leak. Finally, the brand and reputation of entities is one of the cornerstones of commercial relationships. Billions of dollars are spent yearly on marketing campaigns to establish, maintain and repair brands. If libelous, false or misleading claims are made about a person or entity, then they have the right to seek legal recourse. Yet blockchains attempt to permanently preserve history. Like our choice of programming language, there is no ideal solution for Cardano to resolve these concerns in a ubiquitously correct way. Rather, we have to yield to supported opinion again. With respect to the flow of information, this flow is known as a trusted data feed. It has a source and content. Sources have some notion of credibility and incentive to deceive or maintain honesty. Content can be arbitrarily encoded. Given that we intend on supporting trusted hardware in our protocol stack, we have chosen to explore adding support for Professor Ari Juel et al.’s Town Crier Protocol . Assuming the existence of a credible set of data sources, Town Crier permits the secure scraping of web content for use in smart contracts and other applications. WHY WE ARE BUILDING CARDANO  Creative Commons Attribution 4.0 International License Page 30 of 44