Primitive Vector Cipher(PVC): A Hybrid Encryption Scheme based on the Vector Computational Diffie-Hellman (V-CDH) Problem

This work introduces the Primitive Vector Cipher (PVC), a novel hybrid encryption scheme integrating matrix-based cryptography with advanced Diffie-Hellman key exchange. PVC's security is grounded on the established hardness of the Vector Computational Diffie- Hellman (V-CDH) problem. The two-layered design uses HKDF to mask plaintext via a DH-authenticated shared primitive vector and randomize cipher blocks with a per-block offset. This approach eliminates deterministic repetitions and provides strong resistance against linear and known-plaintext attacks. PVC's block-wise structure allows for massive parallelism and excellent linear scaling. Security is formally analyzed, demonstrating INDCPA security under V-CDH. STS protocol integration elevates security toward IND-CCA guarantees.