The key generation device, the encryption device, the decoding device and the encryption system, the key generation method, encryption manner and decoding manner, as for program, and record

摘要

PROBLEM TO BE SOLVED: To provide a hierarchical type ID-based encryption technology, which keeps an ID secret, and in which the size of a cryptogram is independent of the depth of a hierarchy.;SOLUTION: An encryption system includes a key generation device, an encryption device, and decryption devices. The key generation device can use a master secret key S_m and ID (identification information D=[D₁ to D_K]) of the decryption devices to generate hierarchical secret keys S(k) of all hierarchies under a public key P. The encryption device 200 uses the public key P and the identification information D₁ to D_k of the decryption devices to encrypt plain text M, and obtains the cryptogram C(k) for the decryption device of the kth hierarchy. The decryption device of the first hierarchy uses a hierarchical secret key S(1) to decrypt the received cryptogram C(1), and obtains the plain text M. The decryption device of the kth (however, second or later) hierarchy uses a hierarchical secret key S(k-1) of the k-1th decryption device, the cryptogram C(k), and self-identification information D_k to decrypt the received cryptogram C(k), and obtains the plain text M.;COPYRIGHT: (C)2010,JPO&INPIT