Threshold proxy re-encryption (TPRE) can prevent collusion between a single proxy and a delegatee from converting arbitrary files against the wishes of the delegator through multiple proxies, and can also provide normal services even when certain proxy servers are paralyzed or damaged. A non-interactive identity-based TPRE (IB-TPRE) scheme over lattices is proposed which removes the public key certificates. To accomplish this scheme, Shamir's secret sharing is employed twice, which not only effectively hides the delegator's private key information, but also decentralizes the proxy power by splitting the re-encryption key. Robustness means that a combiner can detect a misbehaving proxy server that has sent an invalid transformed ciphertext share. This property is achieved by lattice-based fully homomorphic signatures. As a result, the whole scheme is thoroughly capable of resisting quantum attacks even when they are available. The security of the proposed scheme is based on the decisional learning with error hardness assumption in the standard model. Two typical application scenarios, including a file-sharing system based on a blockchain network and a robust key escrow system with threshold cryptography, are presented.

Liqiang WU;Yiliang HAN;Xiaoyuan YANG;Minqing ZHANG

Key Laboratory of Network and Information Security,Engineering University of People's Armed Police,Xi'an 710086,China;MOE Key Laboratory of Computer Network and Information Security,Xidian University,Xi'an 710071,China

信息与电子工程前沿（英文）

[1]Liqiang WU;Yiliang HAN;Xiaoyuan YANG;Minqing ZHANG-.Identity-based threshold proxy re-encryption scheme from lattices and its applications)[J].信息与电子工程前沿（英文）,2022(02):258-277

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