Lattice-based signcryption with equality test in standard model

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.

Automated summary

Signcryption technology combines public key encryption and digital signatures to provide confidentiality and authenticity simultaneously. It also allows a third party to check if two ciphertexts come from the same message without knowing the content, which is crucial for computing on encrypted data. The proposed lattice-based signcryption scheme ensures security against insider attacks and highlights vulnerabilities in existing lattice-based signcryption methods.