Abstract: A fiat currency transaction is assured with cryptocurrency collateral. The fiat transaction workflow is modified to perform an out-of-band workflow during which one of the parties to the fiat transaction provides a verifiable blockchain (BC) wallet-to-wallet transfer command to move cryptocurrency in a collateralized amount from a wallet of the party to a wallet associated with the other party. The command is not submitted to the BC and is held in abeyance by a cloud service until there is assurance of no fraud at which time the command is deleted. If fraud is reported, the command is sent to the BC for execution and the defrauded party receives the collateralized amount in a wallet associated with the defrauded party.

Abstract: A seller of blockchain-based media of value for fiat currency is matched to a buyer of the blockchain-based media of value. Terms or conditions of a transaction are agreed to between the parties. A transaction identifier for the transaction is created and blockchain-based media of value of the seller is obtained from the seller's wallet. Instructions for a smart contract are created; the smart contract controls release of the blockchain-based media of value based on its terms. The buyer visits a Self-Service Terminal (SST) deposits fiat currency in an amount dictated by the terms and the SST verifies the deposit and notifies the smart contract. The instructions of the smart contract cause the crypto currency to be transferred to the seller's wallet. The deposited fiat currency can be withdrawn at an SST by the seller or credited automatically to a financial account associated with the seller.