This book constitutes the refereed proceedings of the 12th International Conference on Provable Security, ProvSec 2018, held in Jeju, South Korea, in October 2018. Public key encryption, digital signature, symmetric key cryptography, and applications.

On the Leakage of Corrupted Garbled Circuits.- Location-Proof System Based on Secure Multi-Party Computations.- Verifiable Homomorphic Secret Sharing.- Single Private-Key Generator Security Implies Multiple Private-Key Generators Security.- Secure Outsourcing of Cryptographic Circuits Manufacturing.- On the Hardness of Learning Parity with Noise over Rings.- A CCA-Secure Collusion-Resistant Identity-Based Proxy Re-Encryption Scheme.- Multivariate Encryption Schemes Based on the Constrained MQ Problem.- Token-Based Multi-Input Functional Encryption.- On the CCA2 Security of McEliece in the Standard Model.- Efficient Attribute-Based Encryption with BlackBox Traceability.- A Code-Based Linkable Ring Signature Scheme.- Towards Static Assumption Based Cryptosystem in Pairing Setting: Further Applications of DejaQ and Dual-Form Signature.- Digital Signatures from the Middle-Product LWE.- Generic Double-Authentication Preventing Signatures and a Post-Quantum Instantiation.- A Simpler Construction of Identity-Based Ring Signatures from Lattices.- A Generic Construction of Sequential Aggregate MACs from Any MACs.- Length-Preserving Encryption Based on Single-key Tweakable Block Cipher.- Modeling Privacy in WiFi Fingerprinting Indoor Localization.- Security Notions for Cloud Storage and Deduplication.- Forward Secrecy for SPAKE2.- User-Mediated Authentication Protocols and Unforgeability for Key Collision.- BAdASS: Preserving Privacy in Behavioural Advertising with Applied Secret Sharing.- Signcryption with Quantum Random Oracles.- Formal Treatment of Verifiable Privacy-Preserving Data-Aggregation Protocols.