This book constitutes the refereed proceedings of the 7th International Conference on Applied Cryptography and Network Security, ACNS 2009, held in Paris-Rocquencourt, France, in June 2009.

Key Exchange.- Group Key Exchange Enabling On-Demand Derivation of Peer-to-Peer Keys.- Session-state Reveal Is Stronger Than Ephemeral Key Reveal: Attacking the NAXOS Authenticated Key Exchange Protocol.- Secure Pairing of "Interface-Constrained" Devices Resistant against Rushing User Behavior.- How to Extract and Expand Randomness: A Summary and Explanation of Existing Results.- Secure Computation.- Novel Precomputation Schemes for Elliptic Curve Cryptosystems.- Practical Secure Evaluation of Semi-private Functions.- Secure Hamming Distance Based Computation and Its Applications.- Efficient Robust Private Set Intersection.- Public-Key Encryption.- A New Variant of the Cramer-Shoup KEM Secure against Chosen Ciphertext Attack.- An Efficient Identity-Based Online/Offline Encryption Scheme.- Dual-Policy Attribute Based Encryption.- Construction of Threshold Public-Key Encryptions through Tag-Based Encryptions.- Network Security I.- Malyzer: Defeating Anti-detection for Application-Level Malware Analysis.- A New Message Recognition Protocol with Self-recoverability for Ad Hoc Pervasive Networks.- Traitor Tracing.- Breaking Two k-Resilient Traitor Tracing Schemes with Sublinear Ciphertext Size.- Tracing and Revoking Pirate Rebroadcasts.- Authentication and Anonymity.- Efficient Deniable Authentication for Signatures.- Homomorphic MACs: MAC-Based Integrity for Network Coding.- Algorithmic Tamper Proof (ATP) Counter Units for Authentication Devices Using PIN.- Performance Measurements of Tor Hidden Services in Low-Bandwidth Access Networks.- Hash Functions.- Cryptanalysis of Twister.- Cryptanalysis of CubeHash.- Collision Attack on Boole.- Network Security II.- Integrity Protection for Revision Control.- Fragility of the Robust Security Network: 802.11 Denial of Service.- Fast Packet Classification Using Condition Factorization.- Lattices.- Choosing NTRUEncrypt Parameters in Light of Combined Lattice Reduction and MITM Approaches.- Broadcast Attacks against Lattice-Based Cryptosystems.- Partial Key Exposure Attack on CRT-RSA.- Side-Channel Attacks.- How to Compare Profiled Side-Channel Attacks?.- Theoretical and Practical Aspects of Mutual Information Based Side Channel Analysis.- Attacking ECDSA-Enabled RFID Devices.