When change back is due to a customer at a transaction terminal after a cash payment made by the customer during checkout, a code is generated and rendered on a display of the terminal. The customer captures the code with a camera of a customer-operated device causing a mobile application to launch on the device requesting that the customer designate how the customer wants the change back to be provided. The customer can select a loyalty wallet, a digital wallet, and/or a donation wallet for transferring some or all of the change back. The designated amount of the change back is transferred to the customer-selected wallet(s) and any remaining cash bills still due to the customer as remaining change back is provided to the customer and the transaction concludes at the terminal.

Embodiments allocate and synchronize virtual currency balance of a user among multiple user devices. A user profile is maintained at a central server. The user profile stores a total virtual currency balance and a designation of multiple user devices associated with the user. The total virtual currency balance may be divided among and allocated to the multiple user devices, for example, based on usage data associated with each user device. The portion of the total virtual currency balance allocated to each user device may be stored locally at a local wallet of the corresponding user device. The local virtual currency balance on a user device may be used to purchase goods or services, such as playing a game. If the locally stored virtual currency balance of a given user device runs low, the user device may request additional virtual currency from other user devices without contacting the central server.

A system for returning change electronically to a consumer as a result of a cash transaction is provided. The system uses a merchant terminal by bypassing default funds availability authorization performed in consumer to merchant transfers by the terminal. The terminal therefore enables transfer funds from merchant to consumer in an amount which is associated with change due to the consumer upon receipt of the appropriate request and consumer account identifier. In particular aspects, the change is returned in a cryptocurrency.

Embodiments allocate and synchronize virtual currency balance of a user among multiple user devices. A user profile is maintained at a central server. The user profile stores a total virtual currency balance and a designation of multiple user devices associated with the user. The total virtual currency balance may be divided among and allocated to the multiple user devices, for example, based on usage data associated with each user device. The portion of the total virtual currency balance allocated to each user device may be stored locally at a local wallet of the corresponding user device. The local virtual currency balance on a user device may be used to purchase goods or services, such as playing a game. If the locally stored virtual currency balance of a given user device runs low, the user device may request additional virtual currency from other user devices without contacting the central server.

Various embodiments are directed to processing conversions of digital assets to other digital assets. An example method includes determining a source exchange rate for a source digital asset and a fiat currency, determining a target exchange rate for a target digital asset and a fiat currency, and generating an aggregated conversion rate for the source digital asset and the target digital asset using the source exchange rate and the target exchange rate. The method further includes executing a digital asset conversion, which includes causing source digital asset units to be debited from a source digital asset user account and causing target digital asset units to be credited to a target digital asset user account, and subsequently executing fiat currency transactions (e.g., settlements) with a first digital asset exchange system associated with the source digital asset and a second digital asset exchange system associated with the target digital asset.

An apparatus acquires balance information indicating the balance of electronic money from a storage apparatus possessed by a user, and determines the total price of products picked up by the user using an image captured by an image capturing unit configured to capture an image in a store. In a case where the determined total price exceeds the balance, the apparatus outputs information notifying the user that the total price exceeds the balance.

Embodiments of the disclosure are directed to methods and systems for enabling generation and management of a secondary account. The secondary account may be generated in relation to a primary account, such that at least a portion of a transaction conducted using the secondary account may be charged to the primary account. In some embodiments, the secondary account may be associated with a number of protocols to be applied to a transaction. When a transaction is initiated using the secondary account, a service provider may consult an itinerary to dynamically generate a set of protocols which is relevant to the transaction based on a time period during which the transaction is initiated. In some embodiments, portions of the transaction may be split up and transmitted to different authorization entities for authorization.

A method for optimizing blockchain storage size through use of relative values includes: receiving, by a blockchain node in a blockchain network that manages a blockchain, a plurality of blockchain data values, each including unspent transaction outputs, at least one destination address, and, for each destination address, an original currency amount; identifying a base value; modifying the original currency amount included in each blockchain data value to be a relative currency amount based on a difference between the identified base value and the original currency amount; generating a new block, the new block including a block header and the modified plurality of blockchain data values; and transmitting the generated new block to a plurality of additional nodes in the blockchain network.

A method of validating a multi-party consensus over a limited connection comprising a validating device configured to transmit a query having a finite number of possible valid answers to a plurality of computing nodes via a unidirectional secure communication channel, receive a limited length string computed based on an aggregated response aggregating a plurality of responses each computed for a multi-party consensus answer to the query by each of at least some of the plurality of computing nodes using a respective secret component, compute a plurality of locally computed strings each computed based on a respective one of the finite number of possible valid answers using an aggregated secret aggregating the plurality of secret components, validate the multi-party consensus answer by comparing the received limited length string to each of the plurality of locally computed strings and initiating one or more operations according to an outcome of the validation.

Embodiments include a method of transferring math-based currency (MBC) funds from a source account associated with a customer computing device to a recipient account associated with a merchant computing system at a merchant physical location comprising a reading device for payment instrument. The method includes receiving a request for an MBC transaction token, generating the MBC transaction token, sending the MBC transaction token to the customer computing device. The method further includes receiving, from the merchant computing system, the MBC transaction token, determining the MBC transaction token is associated with the mobile wallet account, creating a public and private key pair for the MBC transaction. The method further includes signing and broadcasting the MBC transaction to MBC verification nodes, determining the MBC transaction was verified, transmitting an approval message.