Systems, methods, and computer-readable storage media utilized for processing open loop math based currency (“MBC”) credit card transactions at a financial institution. One method includes receiving, via an open loop processing network, a request for an MBC transaction and generating a first code uniquely identifying the MBC transaction. The method further includes transmitting, via the open loop processing network, the first code to the customer computer device and receiving, from an acquirer/processor computer system via the open loop processing network, a second code including the first code and a public and private key pair. The method further includes determining that the public key is registered and updating a first entry of an overlay ledger and a second entry of the overlay ledger. The method further includes transmitting, via the open loop processing network, a credit guarantee and transmitting, via the open loop processing network, a receipt of the MBC transaction.