Title Online Advertising: Secure E-coupons Authors Stelvio Cimato, Dipartimento di Informatica ed Applicazioni - Università degli Studi di Salerno  Annalisa De Bonis, Dipartimento di Informatica ed Applicazioni -Università degli Studi di Salerno Main Fields 5. cryptography 24. security Other Main Fields Abstract + Keywords A form of advertisement which is becoming popular on the web is based on digital coupon ({\em e-coupon}) distribution. E-coupons are the digital analogue of paper coupons which are used to provide customers with incentives to buy some merchandise. Nowadays, the potential of digital coupons has not been fully exploited on the web. This is mostly due to the lack of an efficient'' protocol for e-coupon distribution which ensures that e-coupons are released by advertisers according to the merchant's specification and that customers use them properly. In this paper we propose a protocol for e-coupons which satisfies these security requirements. Our protocol is lightweight and preserves users privacy since it does not require users' registration.