The Centre for Computer and Information Security Research (CCISR) invites you to attend the Crypto Seminar with the following detail:
Date/time: Tuesday 15 Nov 1.30pm-2.30pm
Venue: 214 Infrastructure Security Lab, Smart Building
- The first talk: Title: A Privacy Preserving Source-verifiable Encryption Scheme
Speaker: Zhongyuan Yao
Abstract: It is critical to guarantee message confidentiality and user privacy in communication networks, especially for group communications. We find previous works seldom consider these aspects at the same time and some trivial solutions cannot remain secure under strong security models, IND-CCA2 for example. In order to address the aforementioned problem properly, we propose a privacy-preserving source-verifiable encryption scheme. With our scheme, the sender can prove his legitimation to anyone in a set of users chosen by himself without leaking his identity, and only the intended receiver can retrieve the original message and the identity of the sender from a given ciphertext. Considering the security of our scheme, we define three security models which capture the message confidentiality, the user privacy and the user impersonation resistance respectively. We prove that our scheme maintains all the three aforementioned properties under the random oracle model.
- The second talk:
Title: Achieving IND-CCA Security for Functional Encryption for Inner Products
Speaker: Shiwei Zhang
Abstract: Functional encryption allows the authorised parties to reveal partial information of the plaintext hidden in a ciphertext while in conventional encryption decryption is all-or-nothing.Focusing on the functionality of inner product evaluation (i.e. given vectors x and y, calculate xy), Abdalla et al. (PKC 2015) proposed a functional encryption scheme for inner product functionality (FE-IP) with s-IND-CPA security.In some recent works by Abdalla et al. (eprint: Report 2016/11) and Agrawal et al. (CRYPTO 2016), IND-CPA secure FE-IP schemes have also been proposed.In order to achieve Indistinguishable under Chosen Ciphertext Attacks (IND-CCA security) for FE-IP, in this paper, we propose a generic construction of FE-IP from hash proof systems.We prove the constructed FE-IP is IND-CCA secure, assuming the hardness of the subset membership problem.In addition, we give an instantiation of our generic construction from the DDH assumption.