An efficient on-line electronic cash with unlinkable exact payments

Toru Nakanishi, Yuji Sugiyama

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Though there are intensive researches on off-line electronic cash (e-cash), the current computer network infrastructure sufficiently accepts on-line e-cash. The on-line means that the payment protocol involves with the bank, and the off-line means no involvement. For customers' privacy, the e-cash system should satisfy unlinkability, i.e., any pair of payments is unlinkable w.r.t. the sameness of the payer. In addition, for the convenience, exact payments, i.e., the payments with arbitrary amounts, should be also able to performed. In an existing off-line system with unlinkable exact payments, the customers need massive computations. On the other hand, an existing on-line system does not satisfy the efficiency and the perfect unlinkability simultaneously. This paper proposes an online system, where the efficiency and the perfect unlinkability are achieved simultaneously.

Original languageEnglish
Pages (from-to)2769-2777
Number of pages9
JournalIEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences
Issue number10
Publication statusPublished - Oct 2005


  • Exact payments
  • On-line e-cash
  • Paillier cryptosystem
  • Unlinkability
  • Zero-knowledge proofs of knowledge

ASJC Scopus subject areas

  • Signal Processing
  • Computer Graphics and Computer-Aided Design
  • Electrical and Electronic Engineering
  • Applied Mathematics


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