This book constitutes the refereed proceedings of the 12th IMA International Conference on Cryptography and Coding, held in Cirencester, UK in December 2009. The 26 revised full papers presented together with 3 invited contributions were carefully reviewed and selected from 53 submissions. The papers are organized in topical sections on coding theory, symmetric cryptography, security protocols, asymmetric cryptography, Boolean functions and side channels and implementations.

Inhalt
Coding Theory.- Subspace Codes.- On Linear Programming Decoding on a Quantized Additive White Gaussian Noise Channel.- Codes as Modules over Skew Polynomial Rings.- On Higher Weights and Code Existence.- Mass Formula for Even Codes over .- On the Classification of Self-dual -Codes.- On Linear Codes from Maximal Curves.- Symmetric Cryptography.- On Linear Cryptanalysis with Many Linear Approximations.- Bivium as a Mixed-Integer Linear Programming Problem.- Security of Cyclic Double Block Length Hash Functions.- Another Glance at Double-Length Hashing.- Geometric Ideas for Cryptographic Equation Solving in Even Characteristic.- Security Protocols.- Provably Secure Code-Based Threshold Ring Signatures.- A New Protocol for the Nearby Friend Problem.- Distributing the Key Distribution Centre in SakaiKasahara Based Systems.- Key Predistribution Schemes and One-Time Broadcast Encryption Schemes from Algebraic Geometry Codes.- Attribute-Based Encryption Supporting Direct/Indirect Revocation Modes.- Certificate-Free Attribute Authentication.- Asymmetric Cryptography.- Comparing with RSA.- Double-Exponentiation in Factor-4 Groups and Its Applications.- Oracle-Assisted Static Diffie-Hellman Is Easier Than Discrete Logarithms.- An Improvement to the Gaudry-Schost Algorithm for Multidimensional Discrete Logarithm Problems.- Boolean Functions.- On Designs and Multiplier Groups Constructed from Almost Perfect Nonlinear Functions.- A New Family of Hyper-Bent Boolean Functions in Polynomial Form.- The Rayleigh Quotient of Bent Functions.- Side Channels and Implementations.- Cache Timing Analysis of LFSR-Based Stream Ciphers.- Optimal Recovery of Secret Keys from Weak Side Channel Traces.- Practical Zero-Knowledge Proofs for Circuit Evaluation.