An ID-Based Efficient Signcryption Key Encapsulation Scheme

Hybrid schemes in a KEM-DEM structure is regarded as the most natural approach to public key encryption with IND-CCA security and practical efficiency. Traditional KEM is realized by public key scheme, which only provides confidentiality security for session key used by DEM. In 2005, combining the idea of signcryption with the KEM-DEM model hybrid encryption, Alexander proposed a signcryption KEM-DEM model hybrid signcryption primitive. Signcryption KEM means that the senders private key and the receivers public key are used together to generate session key and key encapsulation. Compared with traditional KEM scheme, Signcryption KEM can provide both confidentiality security and unforgeability security for session key. In this paper the definition of signcryption KEM is extended in ID-based cryptography. Based on Sakai-Kasahara identity-based key contracture and elliptic-curves-related hard problems, an instance scheme of ID-based signcryption key encapsulation is proposed. Security properties of the proposed scheme are proven with the random oracle model. The proposed scheme is ID-IND-CCA secure in confidentiality and ID-UF-CMA secure in unforgeability. At the encapsulation phase of the proposed scheme, no paring computing and no MapToPoint hash function are required. According to the recent advances in pairings optimized computing and point reduction, the proposed scheme is not only secure but also has advantage in performance.