International Association for Cryptologic Research

International Association
for Cryptologic Research

IACR News item: 10 December 2019

Fei Meng, Mingqiang Wang
ePrint Report ePrint Report
Ciphertext-policy attribute-based encryption (CP-ABE) is a cryptographic technique known for ensuring fine-grained access control on encrypted data. However, one of the main drawbacks of CP-ABE is that the time required to decrypt the ciphertext is considerably expensive, since it grows with the complexity of access policy. Outsourcing partial decryption operations to the cloud eliminates the overheads for users, but it also inevitably increases the computational burden of the cloud. When millions of users are enjoying cloud computing services, it may cause huge congestion and latency.

In this paper, we propose a heuristic primitive called reverse outsourcing. Specifically, users outsource part of the decryption work to the cloud, which splits it up and dispatches each to different idle users. Idle users are those whos has some smart devices connected to the internet and not in use. It's like, the cloud employs many idle users to accomplish its own computing tasks. Then, we proposed a reverse outsourced CP-ABE scheme which provable secure under the BDBH assumptions.
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