Lattice-based Signcryption with Equality Test in Standard Model
This scheme provides a secure method for cloud servers to perform equality tests on encrypted data, which is crucial for privacy-preserving computation.
This paper introduces the first lattice-based signcryption scheme that allows a third party to test for message equality between two ciphertexts without revealing the messages. The scheme is proven secure against insider attacks under the learning with errors and short integer solution assumptions.
A signcryption, which is an integration of a public key encryption and a digital signature, can provide confidentiality and authenticity simultaneously. Additionally, a signcryption associated with equality test allows a third party (e.g., a cloud server) to check whether or not two ciphertexts are encrypted from the same message without knowing the message. This application plays an important role especially in computing on encrypted data. In this paper, we propose the first lattice-based signcryption scheme equipped with a solution to testing the message equality in the standard model. The proposed signcryption scheme is proven to be secure against insider attacks under the learning with errors assumption and the intractability of the short integer solution problem. As a by-product, we also show that some existing lattice-based signcryptions either is insecure or does not work correctly.