In this paper, we construct a new identity-based signcryption scheme from bilinear pairings, which can process arbitrary length plaintexts. The scheme produces shorter ciphertext than the Libert-Quisquater signcryption scheme for the same plaintext and adapts to the bandwidth-constrained scenario very well. It is proved secure against adaptive chosen ciphertext and identity attack based on a variant of the Bilinear Diffie-Hellman problem in the random oracle model.