分野別セミナー

In a proxy re-encryption (PRE) scheme, a semi-trusted proxy is allowed to transform a ciphertext under Alice's public key into a new ciphertext under Bob's public key on the same message. However, the proxy cannot learn any information about the messages encrypted under the public key of either Alice or Bob. Due to the nature of PRE, it has received plenty of attention from the research community as fundamental cryptographic function to solve key management problems in various practical applications. In this talk, we introduce the notion of PRE and the definitions for secure PRE schemes. We also give notable PRE schemes according to their characteristics.