To improve the real-time efficiency of proxy re-signature schemes, a notion called divisible on-line/off-line proxy resignatures is introduced in this paper. The idea of this notion is to split the re-signing algorithm into two phases: the off-line and on-line phases. The proxy can perform the bulk of re-signature computation in the off-line phase before seeing the message to be re-signed. The results of this pre-computation are saved and then used in the on-line phase after the message to be re-signed is given. Divisible on-line/off-line proxy re-signatures are very useful in a particular scenario where the proxy must respond quickly once the message to be re-signed is presented. In a divisible on-line/off-line proxy re-signature scheme, the partial re-signature might be exposed before the message to be re-signed arrives. We then propose a generic divisible on-line/off-line proxy re-signature scheme, which can transform any proxy re-signature scheme into a highly efficient divisible on-line/off-line proxy re-signature scheme. Compared to existing proxy re-signature schemes, our scheme demonstrates higher efficiency. The security of the scheme relies on the unforgeability of its underlying proxy re-signature scheme and the difficulty to solve the discrete logarithm problem.
Yang, Xiaodong; Li, Chunmei; Li, Yan; Zhou, Sian; and Wang, Caifen
"Divisible On-Line/Off-Line Proxy Re-Signature,"
Applied Mathematics & Information Sciences: Vol. 09
, Article 24.
Available at: https://dc.naturalspublishing.com/amis/vol09/iss2/24