| The perfect combination of Internet, mobile communication and computer creates electronic commerce. Due to its agility, simpleness and convenience, electronic commerce is popular with consumers. However, the security is the biggest problem. The key technology to guarantee the security of electronic commerce is cryptogram. The encrypting technology and digital signature are important components of security technology of electronic commerce.The system of secret sharing is a very important branch of modern cryptology, and an important content of information security. In addition, because of the characteristics of elliptic curve cryptosystem, such as more security, short length of key, quickly encrypting and decryting, this paper mainly focuses on the elliptic curve cryptosystem based on the threshold secret sharing and the scheme of elliptic curve digital signature. The main work is as follows:Firstly, combining the key cryptosystem and threshold secret sharing, we propose a threshold elliptic curve cryptosystem. In this system the key distribution center makes several receivers sharing the key. Only when the amount of receivers isn't less than the threshold value can they decrypt the received information jointly. This scheme has secrecy of data and robustness etc.Secondly, according to the above system, the standard scheme of elliptic curve digital signature is amended and a scheme of elliptic curve encrypt digital signature based on threshold is proposed. Besides the characteristic of the above scheme, this scheme completes the encrypting information and signature together. This will improve the efficiency of original scheme's encrypting and signature.In these two schemes, as long as the receivers give the shadow of the sub-key, the shadow of the group key can come back. In this way, the group key and participants'sub-keys can be used repeatedly and can find out whether there is cheater among participants or not. All of their security is based on elliptic curve discrete logarithm problem. |
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