Identity based cryptographic method for encrypting and decrypting e.g. electronic message, involves encrypting message using symmetric encryption key and broadcasting cryptogram and encrypted message from transmitting entity

摘要

The method involves generating a symmetric encryption key (k) by an encryption key generator (23) and generating a cryptogram (Hdr) associated to the encryption key based on a public key, identity parameters of receiver entity and an integer chosen by a transmitting entity (2). The cryptogram is generated so as to provide access to the encryption key by combination with the public key, the parameters and a private key of receiver entity. A message is encrypted in the entity (2) using the encryption key, and the cryptogram and the encrypted message(C-M) are broadcasted from the entity (2). Independent claims are also included for the following: (1) an encryption device, comprising a memory (2) a decryption device, comprising a memory for containing a public key (3) a computer program for encryption device, comprising instructions for implementing encryption operation of identity based cryptographic method (4) a computer program for decryption device, comprising instructions for implementing decryption operation of identity based cryptographic method (5) a data medium for recording a program for implementing decryption operation of identity based cryptographic method.