To browse Academia. This paper revisits the concept of sanitizable signatures, originally developed in the context of proxy re-encryption, which allows encrypted data to be re-encrypted by a proxy without revealing the plaintext to the proxy.
The study highlights the need for secure methods that do not rely on costly operations, such as bilinear pairings, while also addressing security against chosen-ciphertext attacks. Through the exploration of different models and constructions, the authors propose improvements and new approaches to support efficient sanitizable signatures under various adversarial conditions. A proxy re-encryption scheme enables a proxy to re-encrypt a ciphertext and designate it to a delegatee.
Proxy re-encryption schemes have been found useful in many applications, including e-mail forwarding, law-enforcement monitoring, and content distribution. Libert and Vergnaud presented the first construction of unidirectional proxy re-encryption scheme with chosen ciphertext security in the standard model in PKC In this paper, we show the insecurity of Libert and Vergnaud's scheme against chosen public key attack.
We note that this insecurity is not considered in the original model proposed by Libert and Vergnaud's, but we argue that our attack is very realistic and important in this scenario. Furthermore, we present a new and efficient construction proxy re-encryption PRE scheme. We provide chosen public key and chosen ciphertext attack security analysis for our scheme and compare their performance.
Proxy re-encryption PRE allows a semi-trusted proxy to convert a ciphertext originally intended for Alice into one encrypting the same plaintext for Bob. The proxy only needs a re-encryption key given by Alice, and cannot learn anything about the plaintext encrypted. This adds flexibility in various applications, such as confidential email, digital right management and distributed storage.
