Method and apparatus for implementing hierarchical electronic cash

US5926548A · kind A · utility

Assignee

• NIPPON TELEGRAPH AND TELEPHONE CORPORATION · JP

Inventor

• Tatsuaki Okamoto · Musashino, JP

Key dates

• Filing date: May 20, 1997
• Grant date: Jul 20, 1999
• Expiry date: May 20, 2017

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04L2209/56
• WIPO field: IT methods for management
• WIPO sector: Electrical engineering

Abstract

A user U generates a signature verification key N.sub.U, a signature key SS.sub.U and a cipher key K, enciphers (X,N.sub.U) by a public key into E.sub.I (X,K,N.sub.U) and sends the enciphered information to a bank together with user information U and the amount of money X. The bank registers the information U and E.sub.I in a user data base in correspondence with each other, then withdraws the amount of money X from a user's bank account and sends information (X,E.sub.I) to an electronic cash issuer together with a bank signature S.sub.B (X,E.sub.I) for the information. The issuer deciphers the enciphered information E.sub.I by a secret key to obtain the information (X,N.sub.U), then registers the information E.sub.I and the key N.sub.U in an inspection data base in correspondence with each other, and enciphers the signature S.sub.I (X,N.sub.U) attached to the key N.sub.U by the key K into E.sub.K (S.sub.I), which is sent to the user via the bank. The user deciphers the information E.sub.K by the key K to obtain the issuer signature S.sub.I and sends to a shop, as electronic cash C, information containing the key N.sub.U and the issuer signature S.sub.I. The shop verifies the valid…