摘要 |
A high speed copy protection method including encrypting a first region of a text containing a second encryption key data using a first encryption key, and encrypting a second region of the text using a second encryption key based upon the second encryption key data, and transmitting a cipher text. A large amount of cipher text data requiring high speed processing are processed using the second encryption key, which is a key used in a common key encryption method, and a smaller part of the cipher text data are processed using a larger first encryption key as used in a common key or a public key encryption method, thereby satisfying speed and security. |