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The newly introduced notion of Asymmetric Group Key Agreement (AGKA) enables external users to securely send messages to group members. The existing AGKA is only secure against passive attacks which are too weak to capture the attacks in the real world. In this paper, the authors formalize an active security model for Identity-Based Authenticated Asymmetric Group Key Agreement (IB-AAGKA). They then present an efficient identity-based batch multi-signature, from which they construct an IB-AAGKA protocol. Their protocol is proven secure under the Bilinear Diffie-Hellman Exponent (BDHE) assumption. The active security feature implies that the protocol can with-stand more realistic attacks.