Wang, S.Cao, Z.Choo, K.K.Wang, L.2025-12-172025-12-172009Information Sciences, 2009; 179(3):307-3180020-0255https://hdl.handle.net/1959.8/120170We revisit the identity-based (ID-based) key agreement protocol due to Ryu et al. The protocol is highly efficient and suitable for real-world applications despite offering no resilience against key-compromise impersonation (K-CI). We show that the protocol is also insecure against reflection attacks. We propose a slight modification to the protocol and prove its security in a widely accepted model.enCopyright 2009 Elsevierkey agreement protocolsreflection attackprovable securitymodular proofPKG forward secrecyJournal article10.1016/j.ins.2008.09.0202-s2.0-55949109421