| Title | : | Achieving collusion-resistant unidirectional proxy re-encryption without pairing in the random oracle model |
| Speaker | : | Arinjita Paul (IITM) |
| Details | : | Tue, 28 Jan, 2020 2:00 PM @ AM Turing Hall |
| Abstract: | : | Proxy re-encryption (PRE) enables delegation of decryption rights by entrusting a proxy server with special information, that allows it to transform a ciphertext under one public key into a ciphertext of the same message under a different public key. It is important to note that, the proxy which performs the re-encryption operation learns nothing about the message encrypted under either public keys. Due to its transformation property, proxy re-encryption schemes have practical applications in blockchain-enabled storage, encrypted email forwarding, Digital Rights Management (DRM) among others. From its introduction, several proxy re-encryption schemes have been proposed in the literature, and a majority of them have been realized using bilinear pairing, which is an expensive operation. Despite recent advances in implementation techniques, bilinear pairing takes more than twice the time taken by modular exponentiation computations in finite fields. In Africacrypt 2010, the first PKI-based collusion resistant CCA secure PRE scheme without pairing was proposed in the random oracle model. In our work, we point out an important weakness in the scheme. We also present the first collusion-resistant pairing-free unidirectional proxy re-encryption scheme which meets CCA security under a variant of the Computational Diffie-Hellman hardness assumption in the random oracle model. |
