Patent ID: 6788788
Filing Date: 2004-09-07
Classification: H04L

Abstract:
A cryptographic communication method for communication of information between entities, in which an entity-specific secret key is generated at a center and sent to each entity from the center, one entity uses a common key determined from its own entity-specific secret key sent from the center and a publicly known public key of the other entity to encrypt a plaintext into a ciphertext and transmits the ciphertext to the an other entity, and the other entity uses the same common key as said common key, determined from its own entity-specific secret key sent from the center and a publicly known public key of the one entity, to decrypt said ciphertext sent from the one entity back into a plaintext,characterized in that each of said entity-specific secret keys includes at least one type of secret key selected from a plurality of types of secret keys in which each of a plurality of numbers serves as a modulus, said secret keys generated using said respective entities' public key and entity-specific random number, the one entity uses a plurality of its own said plural types of secret keys and the public key of the other of said entities to generate said common key, and the other of said entities uses a plurality of its own said plural types of secret keys and the public key of the one entity to generate said common key, and wherein said public key of each entity is determined by utilizing a hash function with specific information of each entity.