The Improvement And Implementation Of An Identity-Based Authenticated Encryption Scheme

Identity Based cryptography is a rapidly emerging approach to public-key cryptography that does not require principals to pre-compute key pairs and obtain certificates for their public keys-instead, public keys can be arbitrary identifiers such as email addresses, while private keys are derived at any time by a trusted private key generator upon request by the designated principals.Combining the identity-based cryptographic systems and the traditional symmetric encryption method, an identity-based authenticated encryption scheme which was more efficient than before was proposed recently in an article named 'A new Identity-based Authenticated Encryption Scheme'. At the same time, a weakness was presentd in that scheme—a recipient can pretend other users to send messages to him, that is, users can't authenticate whether a message's sender is true.In this thesis, we propose an improvement of that scheme, whose security is based on the bilinear Diffie-Hellman problem. During the process of encrypting, the sender calculates the ciphertext and the authenticate messages. The recipient first verifies the sender's identity with authenticate messages. The process of decrypting is enforced, only the sender's identity is true. Our scheme not only overcomes the mentioned weakness, but also keeps the excellence of that scheme.Finally, we show the programs developed by Visual C++ 6.0 under Windows, which have implemented this improve scheme.