To obtain a ciphering method which keeps an issuer side safe and also represents funds in safe form even when the funds are moved from a payer to a recipient, and returned to the issuer by transferring a message to an issuer's terminal and ciphering the contents of the message so that they can be interpreted only on the issuer terminal.
A coin is an object consisting of a unique identifier 11 called a coin ID, face value 12, an expiration date 13, and an authentication code tag 14. The tag 14 is MAC(message authentication code) and calculated for other fields (coin ID 11, face value 12, and expiration date 13) by using a symmetrical key (random number selected by the issuers), and its secrecy is held by the issuer. Therefore, the issuer can calculate and confirm the tag 13, but if a 3rd party is unable to calculate the effective tag 14. The ciphering method based upon the symmetrical key is hundreds of times as efficient as before.
JUAN ALBERTO GAREY
CHARANJITTO SHIN JURUTA
MARCEL MORDECHAI YUN
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