Gave three properties of decryption key in RSA system: infinite property, constructive property, same odd type property.

The pre-distribution scheme of the key for wireless sensors networks with actors;

A Cipher Algorithm with Variable Keys;

Research and application of multiple-threshold key sharing;

A quick way to acquire the secret key of WPS file encrypted;

The method implements the random creation of secret key and the random call of encryption algorithm,which can increase .

Finally,the management and assignment of secret key in data encryption devices and data networks.

In view of the deficient application of short cryptographic keys in DES algorithm,this paper presents the conception of developing DES key space by the chaotic theory and designs a new DES algorithm based on logistic chaotic sequences.

The algorithm generate DES cryptographic key by Lorenz chaos equations,greatly expanding the DES encryption algorithm cryptographic key space.

EFS use advanced and standard encrypt arithmetic to achieve transparent encrypt and decrypt any individual or program without appropriate cryptographic key is unable to neither read nor write encrypted data.

Encryption technique of the computers is expouned,public encryption key,private encryption key,digital signature,and digital certificate are analyzed,and the module card for interfacing the Microsoft integration with CryptAPI(cryptographic application program interface) in the browser of IE software as well as the basic functions are introduced.