Encryption method, decryption method, encryption/decryption method, cryptographic communications system, and computer usable medium

摘要

An encryption/decryption method applicable to product-sum cryptosystem. This method enables highspeed decryption. A ciphertext C=m₀B₀+m₁B₁+ . . . +m_K−1B_K−1 is produced from a scalar product of a plaintext vector m=(m₀, m₁, . . . , m_K−1) and a base vector B=(B₀, B₁, . . . , B_K−1).