Anamorphic Encryption with CCA Security: A Standard Model Construction

• URL: http://arxiv.org/abs/2604.07771v1
• Date: Thu, 09 Apr 2026 03:49:41 GMT
• Title: Anamorphic Encryption with CCA Security: A Standard Model Construction
• Abstract summary: Anamorphic encryption serves as a vital tool for covert communication, maintaining secrecy even during post-compromise scenarios.<n>We formalize the Anamorphic Key Encapsulation Mechanism (AKEM), encompassing both Public-Key (PKAKEM) and Symmetric-Key (SKAKEM) variants.<n>We provide a rigorous formal proof in the standard model, demonstrating resilience against a "dictator" who controls the decapsulation key.
• Score: 32.95661036494699
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Anamorphic encryption serves as a vital tool for covert communication, maintaining secrecy even during post-compromise scenarios. Particularly in the receiver-anamorphic setting, a user can shield hidden messages even when coerced into surrendering their secret keys. However, a major bottleneck in existing research is the reliance on CPA-security, leaving the construction of a generic, CCA-secure anamorphic scheme in the standard model as a persistent open challenge. To bridge this gap, we formalize the Anamorphic Key Encapsulation Mechanism (AKEM), encompassing both Public-Key (PKAKEM) and Symmetric-Key (SKAKEM) variants. We propose generic constructions for these primitives, which can be instantiated using any KEM that facilitates randomness recovery. Notably, our framework achieves strong IND-CCA (sIND-CCA) security for the covert channel. We provide a rigorous formal proof in the standard model, demonstrating resilience against a "dictator" who controls the decapsulation key. The security of our approach is anchored in the injective property of the base KEM, which ensures a unique mapping between ciphertexts and randomness. By integrating anamorphism into the KEM-DEM paradigm, our work significantly enhances the practical utility of covert channels within modern cryptographic infrastructures.

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