A Secure Proxy Re-Signature Scheme for IoT
In a proxy re-signature (PRS) scheme, a semi-trusted proxy is able to transform a signature signed by a user to a new signature of the same message signed by another user, it however cannot sign on any other message on behalf of those users. PRS thus has found many practical applications such as distributed storage, distributed rights management or cloud infrastructure. To our knowledge, all of the PRS schemes without using random oracle (RO for short) need to use the Waters’ hash function, which leads to PRS schemes with large key size and inefficient computing time. In this paper, we propose a new bidirectional PRS scheme without using RO and without using the Waters’ hash function. Our scheme is therefore the best PRS scheme without using RO to date in term of efficiency.