To be viable, any currency, whether emitted by a computer program of crypto currency or a traditional "fiat" currency issued by the government, must win the trust of the community that uses it. For the advocates of crypto currency, the whole point is to suggest an alternative model of this trust. They promote a payment system where recipients no longer need to trust outside institutions, be they banks or governments, to ensure that the payer is able to provide the agreed funds. Instead, the crypto-currency systems give credence to an indestructible decentralized computer program, unable, theoretically, to deceive people.