International Association
for Cryptologic Research

Ecash is a concept of electronic cash which would allow users to carry money in form of digital coins. Transaction can be done both offline and online in absence of a third party/financial institution. This paper proposes an offline model which supports multiple usage of transferable ecoin. The protocol is based on RSA, digital signature and a two-step encryption process. In this two step encryption, the user account details are encrypted in the coin using unique numbers in each step. The first encryption takes place during the successful receipt of the coin, where a receive end number is used for encryption,which is unique for every receipt. The second step of encryption takes place during successful spending of the coin,where a spending end receive number is used for encryption, which is unique for every spenfing of the coin. These two unique numbers comprise the major part of encryption in this model, prevents double spending and preserves user anonymity.