Abstract: An anti-alteration system for Web contents is described. A public-web-server computer stores safe web files encrypted from the original web contents, including static files (such as html, text, jpg, gif, wav, mp3, asp, exe, etc.) and dynamic files (such as php, perl, java script, etc.). An original-Web-server computer stores the original web content and connects to the public-web-server computer through a protected access port such as a firewall. When a website visitor's request is received, the public web server checks the safe web file, and if the safe Web file has not been altered, the web server sends back the web content decrypted from the safe web file. A recovery module is used for encrypting the web content to the safe web file on the original web server computer.

Abstract: An anti-alteration system for homepage, which can prevent web server sending illegally changed data to user absolutely, includes a public-web-server computer which retention the safe-web-files encrypted and added with the prohibit illegally alter header from the usual web files (html, txt, gif, jpg, jpeg, au, exe, etc.

Abstract: In an encryption and decryption system, information in plaintext is encrypted by adding to each group of signals in the information a digital chaos signal in accordance with a chaos function, a delay, an initial value, and parameters of the chaos function determined using a cryptographic key which can be any length and any combination of letters, numerals, or words. The encrypted information is decrypted by decrypting each group of signals in the encrypted information using a digital chaos signal which is generated using the same key as that used in the encryption. Accordingly, it is possible to provide enhanced secrecy and to perform encryption and decryption of information at high speed.