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On The Security Of Two Identity-Based Conditional Proxy Re-Encryption Schemes, Kai He, Jian Weng, Robert H. Deng, Joseph K. Liu
On The Security Of Two Identity-Based Conditional Proxy Re-Encryption Schemes, Kai He, Jian Weng, Robert H. Deng, Joseph K. Liu
Research Collection School Of Computing and Information Systems
Proxy re-encryption allows a semi-trusted proxy with a re-encryption key to convert a delegator's ciphertext into a delegatee's ciphertext, and the semi-trusted proxy cannot learn anything about the underlying plaintext. If a proxy re-encryption scheme is indistinguishable against chosen-ciphertext attacks, its initialized ciphertext should be non-malleable. Otherwise, there might exist an adversary who can break the chosen-ciphertext security of the scheme. Recently, Liang et al. proposed two proxy re-encryption schemes. They claimed that their schemes were chosen-ciphertext secure in the standard model. However, we find that the original ciphertext in their schemes are malleable. Thus, we present some concrete attacks …
Generic Anonymous Identity-Based Broadcast Encryption With Chosen-Ciphertext Security, Kai He, Jian Weng, Man Ho Au, Yijun Mao, Deng, Robert H.
Generic Anonymous Identity-Based Broadcast Encryption With Chosen-Ciphertext Security, Kai He, Jian Weng, Man Ho Au, Yijun Mao, Deng, Robert H.
Research Collection School Of Computing and Information Systems
In a broadcast encryption system, a broadcaster can encrypt a message to a group of authorized receivers S and each authorized receiver can use his/her own private key to correctly decrypt the broadcast ciphertext, while the users outside S cannot. Identity-based broadcast encryption (IBBE) system is a variant of broadcast encryption system where any string representing the user’s identity (e.g., email address) can be used as his/her public key. IBBE has found many applications in real life, such as pay-TV systems, distribution of copyrighted materials, satellite radio communications. When employing an IBBE system, it is very important to protect the …