Signature scheme and encryption based on the identity of the hierarchical

摘要

How to encode and decode digital messages between a sender and a receiver in a system including private key generator of multiple ("PKG") is provided. Some of PKG, a plurality of root PKG one, and a lower-level PKG the n in the hierarchy between the recipient and the route PKG there is at least. Root key generation secret is selected, this root key generation secret is known only to the root PKG. Root key generation parameter is generated based on the root key generation secret. lower-level key generation secret is selected in each of the lower-level PKG the n. In this case, the lower-level key generation secret is known only to the lower-level PKG its corresponding. Also, by using the lower-level key generation secrets in the lower-level private key generators its corresponding at least to each of the lower-level PKG the n lower-level key generation parameters is generated. By using the recipient identity information associated with the recipient and the root key generation parameter, the ciphertext is generated message is encoded at least. At least, the recipient private key is generated to be associated with one or more of said root key generation secret and the lower-level key generation secret of the n and to the recipient identity information. By using the recipient's private key, the message is restored ciphertext is decoded at least.