Advances in Cryptology — CRYPTO ’91

Volume 576 of the series Lecture Notes in Computer Science pp 324-337


Universal Electronic Cash

  • Tatsuaki OkamotoAffiliated withNTT Laboratorics, Nippon Telegraph and Telephone Corporation
  • , Kazuo OhtaAffiliated withNTT Laboratorics, Nippon Telegraph and Telephone Corporation


This paper proposes the first ideal untraceable electronic cash system which solves the most crucial problem inherent with real cash and all previous untraceable electronic cash systems. The main advantage of the new system is that the customer can subdivide his cash balance, C (dollars), into many pieces in any way he pleases until the total value of all subdivided piece equals C. This system can be implemented efficiently. In a typical implementation, the data size of one piece of electronic cash is less than 100 bytes regardless of the face value of piece, the computation time for each transaction is several seconds, assuming the existence of a Rabin scheme chip. The security of this scheme relies on the difficulty of factoring.