Research On Identity-based Cryptosystem

In the information security field, the public key cryptography has become more and more essential, especially for communication security, digital signature and key management. PKI (public key infrastructure) is public key cryptosystem architecture and is increasingly used. It uses certificate to make user's public key and ID together. Compared with the traditional certificated-based public key cryptography, ID-based public key cryptosystem uses the user's ID information as a public key; it eliminates the need of certificates and simplifies the operation and management of public key. In this case we just need an authority named PKG to authenticate all users, check their rights, then generate and transfer private key. ID-based public key cryptosystem mainly uses bilinear pairings, for example Weil pairing and Tate pairing defined on Elliptic Curve.In this thesis, we begin with the comparisons of the basic conceptions, the characters and so on between public key cryptography and symmetry cryptography. Then we describe the principle and the use of public key cryptography. The introductions of the definition and the structure of PKI are presented. We also discuss the CA, digital certificate and the detailed workflow. We review the elliptic-curve cryptography, the bilinear pairings especially the Weil pairing and the Tate pairing, and several computational difficult problems. Accordingly, we analyse the configuration of the ID-based Encryption.Finally referring to PBC and using VC++, a new Identity-based Encryption Scheme is implemented. This scheme makes use of the bilinear pairings of elliptic curve, and its security is based on the computational Diffie-Hellman assumption and the unilateralism hash function. Due to simple system initialization, efficient encryption and decryption, this scheme is easy to realize.