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Signcryption is a cryptographic primitive that can provide valid solution for authentication and confidentiality. In this paper, an efficient identity-based signcryption scheme from lattice was proposed. Our scheme based on Macciancio and Piekert’s trapdoor generation method and delegate algorithm for lattice. Our main idea is that establish the identity-based system master key via trapdoor generation method for lattice, and extract user’s key by trapdoor delegate algorithm. With the aid of random oracle, we prove that the proposed scheme has CCA security under the learning with errors (LWE) assumption and unforgeability against adaptive chosen messages attacks under the small integer solution (SIS) assumption. Comparison with signature-then-encryption approach shows that our scheme is efficient.