Electronic cash implementing method using a trustee

US5901229A · kind A · utility

Assignee

• NIPPON TELEGRAPH AND TELEPHONE CORPORATION · JP

Inventors

• Eiichiro Fujisaki · Yokosuka, JP
• Tatsuaki Okamoto · Musashino, JP
• Kazuo Ohta · Zushi, JP

Key dates

• Filing date: Nov 4, 1996
• Grant date: May 4, 1999
• Expiry date: Nov 4, 2016

Classification

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

Abstract

In an electronic cash implementing method using a trustee, a user registers his identification information ID.sub.U and anonymous public key N with the trustee and receives a license (B,I). The user processes the license (B,I) by a public key corresponding to the amount to be issued and sends the processed information to a bank to have it attach a blind signature to the information so that the user obtain electronic cash C from the blind signature. The user transmits to a shop the information B,I,C,N and a digital signature that assures the divisional use of the electronic cash. The shop verifies the validity of the information B and C and accepts it as cash and sends a history H of communication with the user to the bank and receives a payment therefrom. The bank places all received communication histories under its supervision and makes a check to see if the amount x spent by the electronic cash C is in excess of its face value X, and if so, informs the trustee of the information N contained in the communication history. The trustee uses the information ID.sub.U thus received to specify the corresponding user identification information ID.sub.U.