Broadcast Attacks against Code-Based Schemes -- On the Security of Hummingbird-2 against Side Channel Cube Attacks -- Full Lattice Basis Reduction on Graphics Cards -- Breaking DVB-CSA -- On the Role of Expander Graphs in Key Predistribution Schemes for Wireless Sensor Networks -- Γ-MAC[H, P] – A New Universal MAC Scheme -- New Universal Hash Functions -- Cryptanalysis of TWIS Block Cipher -- RSA Vulnerabilities with Small Prime Difference -- Combining Multiplication Methods with Optimized Processing Sequence for Polynomial Multiplier in GF(2k). On the Security of Hummingbird-2 against Side Channel Cube Attacks -- Full Lattice Basis Reduction on Graphics Cards -- Breaking DVB-CSA -- On the Role of Expander Graphs in Key Predistribution Schemes for Wireless Sensor Networks -- Γ-MAC[H, P] – A New Universal MAC Scheme -- New Universal Hash Functions -- Cryptanalysis of TWIS Block Cipher -- RSA Vulnerabilities with Small Prime Difference -- Combining Multiplication Methods with Optimized Processing Sequence for Polynomial Multiplier in GF(2k).

This book constitutes the refereed proceedings of the 4th Western European Workshop on Research in Cryptology, WEWoRC 2011, held in Weimar Germany, in July 2011. The 10 revised full papers were carefully reviewed and selected from numerour submissions. The papers span a wide spectrum of topics from foundations of cryptology, upto secret-key cryptosystems and hash functions, public-key cryptosystems, modes of operation, cryptographic protocols, hardware and software implementation of cryptosystems and their integration into secure systems, and applications such as watermarking and code obfuscation.