Providing coupons to customers is one of the most popular methods for vendors to boost their sales and increase customer loyalty. To facilitate the preservation and management, digital coupons have been emerged and widely used in recent years. In practice, the management and delivery of the digital coupon are usually delegated to a reputable third-party platform (called broker) to increase brand exposure and enlarge service scalability. Meanwhile, with the prevalence of online shopping, targeted coupon delivery has become increasingly popular, providing customized coupons only to eligible users whose behavioral profiles match an eligibility strategy specified by the vendor. It enables vendors to benefit from the ease of attracting new customers and building customer loyalty. Despite the intriguing benefits, there are also some drawbacks in providing some services (management and delivery) for targeted coupons by a third-party platform such as the confidentiality of the customized coupons for non-eligible users and the privacy concerns for collecting the users' personal behaviors.

This dissertation presents an algorithmic design for building the first full-fledged system design for privacy-preserving targeted coupon service which uniquely provides comprehensive functionalities to satisfy its practical needs, including: i) privacy-preserving search on the encrypted coupon, ii) privacy-preserving targeted coupon delivery, and iii) privacy-preserving targeted coupon redemption. Firstly, to shrink the delivery list to the coupon collection that users are interested in, we propose a system module for secure coupon search which enables users to search on the encrypted coupons with three types of queries, accommodating from simple single keyword search to the complex case of Boolean queries and range queries. For the single keyword search, we propose a security-enhanced searchable symmetric encryption (SSE) design, which enables users to securely search for the encrypted coupons with some specified queries such as the ``restaurant". For Boolean queries, we propose another security-enhanced SSE design, which enables users to securely search the encrypted coupons with Boolean queries such as searching the coupons offered by the restaurants locating in Hong Kong and serving either Japanese cuisine or Chinese cuisine. For range queries, we propose a security-enhanced order-revealing encryption (ORE) design, which enables users to securely search for encrypted coupons whose discounts fall within a specific range. Secondly, to meet the requirement of targeted coupons, we propose an efficient eligibility test design which ensures that only eligible users can decrypt the ciphertexts of the targeted coupons obtained from the search process. Thirdly, to ensure that the selected coupons can be securely and correctly redeemed and the broker is sure to gain the service fee he deserves in providing the storage and management service for the vendor, we propose a blockchain-empowered coupon redemption design which enables the blockchain to verify the authenticity and validity of the coupon and transfer the user's money to both the vendor and the broker if the coupon passes verification. The presented research would greatly advance the adoption of the targeted coupon service in our daily life to help vendors engage their customers and help customers enjoy the offers from the coupon and claim rewards after redemption.