Session I: Algebraic and Number Theoretical Cryptanalysis (I) -- Total Break of the ?-IC Signature Scheme -- Recovering NTRU Secret Key from Inversion Oracles -- Solving Systems of Modular Equations in One Variable: How Many RSA-Encrypted Messages Does Eve Need to Know? -- Session II: Theory of Public Key Encryption -- Relations Among Notions of Plaintext Awareness -- Completely Non-malleable Encryption Revisited -- Invited Talk I -- Cryptographic Test Correction -- Session III: Digital Signatures (I) -- Off-Line/On-Line Signatures: Theoretical Aspects and Experimental Results -- Construction of Universal Designated-Verifier Signatures and Identity-Based Signatures from Standard Signatures -- Proxy Signatures Secure Against Proxy Key Exposure -- Session IV: Identification, Broadcast and Key Agreement -- Lattice-Based Identification Schemes Secure Under Active Attacks -- Efficient Simultaneous Broadcast -- SAS-Based Group Authentication and Key Agreement Protocols -- Session V: Implementation of Fast Arithmetic -- An Optimized Hardware Architecture for the Montgomery Multiplication Algorithm -- New Composite Operations and Precomputation Scheme for Elliptic Curve Cryptosystems over Prime Fields -- Session VI: Digital Signatures (II) -- Online-Untransferable Signatures -- Security of Digital Signature Schemes in Weakened Random Oracle Models -- A Digital Signature Scheme Based on CVP ??? -- Session VII: Algebraic and Number Theoretical Cryptanalysis (II) -- An Analysis of the Vector Decomposition Problem -- A Parameterized Splitting System and Its Application to the Discrete Logarithm Problem with Low Hamming Weight Product Exponents -- Session VIII: Public Key Encryption -- Certificateless Encryption Schemes Strongly Secure in the Standard Model -- Unidirectional Chosen-Ciphertext Secure Proxy Re-encryption -- Public Key Broadcast Encryption with Low Number of Keys and Constant Decryption Time.

This book constitutes the refereed proceedings of the 11th International Workshop on Practice and Theory in Public-Key Cryptography, PKC 2008, held in Barcelona, Spain, in March 2008. The 21 revised full papers presented together with 1 invited lecture were carefully reviewed and selected from 71 submissions. The papers are organized in topical sections on algebraic and number theoretical cryptoanalysis, theory of public key encryption, digital signatures, identification, broadcast and key agreement, implementation of fast arithmetic, and public key encryption.