The present disclosure presents a method for a card based transaction between a mobile terminal and a service provider system having one or several computer servers. The mobile terminal obtains a CSC from credit card/debit card. The mobile terminal obtains a data seed. The mobile terminal applies a minimal perfect hash function to the CSC as well as the data seed to generate a temporary CSC. The mobile terminal initiates a card based transaction with the service provider system utilizing the generated temporary CSC. The service provider system obtains the temporary CSC and applies a same minimal perfect hash function to the temporary CSC until a match is found between the obtained temporary CSC and one CSC stored at the service provider system. In response to a match the service provider system continues the initiated card based transaction with the mobile terminal.