No abstract

An important advantage of signcryption schemes compared to one pass key exchange protocols is non-interactive non-repudiation (NINR). This attribute offers to the receiver of a signcrypted ciphertext the ability to generate a non-repudiation evidence, that can be verified by a third party without executing a costly multi-round protocol. We propose a computational Diffie-Hellman based insider secure signcryption scheme with non-interactive non-repudiation. Namely, we show that under the computational Diffie-Hellman assumption and the random oracle model, our scheme is tightly insider secure, provided the underlying encryption scheme is semantically secure. Compared to a large majority of the previously proposed signcryption schemes with NINR, our construction is more efficient and it does not use any specificity of the underlying group, such as pairings. The communication overhead of our construction, compared to Chevallier Mâmes' signature scheme is one group element.