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This book constitutes the refereed proceedings of the Cryptographer´s Track at the RSA Conference 2015, CT-RSA 2015, held in San Francisco, CA, USA, in April 2015. The 26 papers presented in this volume were carefully reviewed and selected from 111 submissions. The focus of the track is on following subjects: timing attacks, design and analysis of block ciphers, attribute and identity based encryption, membership, secure and efficient implementation of AES based Cryptosystems, chosen ciphertext attacks in theory and practice, algorithms for solving hard problems, constructions of hash functions and message authentication codes, secure multiparty computation, authenticated encryption, detecting and tracing malicious activities, implentation attacks on exponentiation algorithms and homomorphic encryption and its applications.

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Timing Attacks.- Just A Little Bit More.- Cache Storage Attacks.- Design and Analysis of Block Ciphers.- Analyzing Permutations for AES-like Ciphers: Understanding ShiftRows.- Improved Attacks on Reduced-Round Camellia-128/192/256.- Attribute and Identity Based Encryption Duality in ABE: Converting Attribute Based Encryption for Dual Predicate and Dual Policy via Computational Encodings.- Revocable Hierarchical Identity-Based Encryption: History-Free Update, Security Against Insiders, and Short Ciphertexts.- Membership.- Revisiting Cryptographic Accumulators, Additional Properties and Relations to other Primitives.- Non-Interactive Zero-Knowledge Proofs of Non-Membership.- Secure and Efficient Implementation of AES Based Cryptosystems Implementing GCM on ARMv8.- Higher-Order Masking in Practice: A Vector Implementation of Masked AES for ARM NEON.- Chosen Ciphertext Attacks in Theory and Practice Completeness of Single-Bit Projection-KDM Security for Public Key Encryption.- Format Oracles on OpenPGP.- Algorithms for Solving Hard Problems.- Finding Shortest Lattice Vectors in the Presence of Gaps.- A Simple and Improved Algorithm for Integer Factorization with Implicit Hints.- Constructions of Hash Functions and Message Authentication Codes.- Hash Functions from Defective Ideal Ciphers.- Using an Error-Correction Code for Fast, Beyond-birthday-bound Authentication.- Secure Multiparty Computation.-Efficient Leakage Resilient Circuit Compilers.- Optimally Efficient Multi-Party Fair Exchange and Fair Secure Multi-Party.- Computation.- Authenticated Encryption.- How to Incorporate Associated Data in Sponge-Based Authenticated Encryption.- Cryptanalysis of Ascon.- Detecting and Tracing Malicious Activities Stronger Security Notions for Decentralized Traceable Attribute-Based Signatures and More Efficient Constructions.- Re-encryption Verifiability: How to Detect Malicious Activities of a Proxy in Proxy Re-encryption.- Implementation Attacks on Exponentiation Algorithms.- Exploiting Collisions in Addition Chain-based Exponentiation Algorithms Using a Single Trace.- Cold Boot Attacks in the Discrete Logarithm Setting.- Homomorphic Encryption and Its Applications.- Communication Optimal Tardos-based Asymmetric Fingerprinting. Linearly Homomorphic Encryption from DDH.

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