Device, method, and program for encrypton and decryption and recording medium

A stream cipher encrypting method of exclusively ORing key data and information data and generating cipher text, the encrypting method comprising the steps of:

• inputting a synchronization signal, extracting a part of data from cipher text at the preceding time, and generating key data with the extracted part of cipher text;
• and
• encrypting the information data with the key data.

A program that causes a computer to execute a stream cipher encrypting method of exclusively ORing key data and information data and generating cipher text, the encrypting method comprising the steps of:

• inputting synchronization data, extracting a part of data from cipher text at the preceding time, and generating key data with the extracted part of cipher text;
• and
• encrypting the information data with the key data.

A computer readable recording medium on which a program that causes a computer to execute a stream cipher encrypting method of exclusively ORing key data and information data and generating cipher text has been recorded, the encrypting method comprising the steps of:

• inputting synchronization data, extracting a part of data from cipher text at the preceding time, and generating key data with the extracted part of cipher text;
• and
• encrypting the information data with the key data.

A stream cipher decrypting apparatus that exclusively ORes cipher text and key data and decrypts the cipher text, the decrypting apparatus comprising:

• key data generation means for inputting a synchronization signal, extracting a part of data from the cipher text at the preceding time, and generating key data with the extracted part of the cipher text;
• and
• decryption means for decrypting the cipher text with the key data.

A stream cipher decrypting method of exclusively ORing cipher text and key data and decrypting the cipher text, the decrypting method comprising the steps of:

• inputting a synchronization signal, extracting a part of data from the cipher text at the preceding time, and generating key data with the extracted part of the cipher text;
• and
• decrypting the cipher text with the key data.

A program that causes a computer to execute a stream cipher decrypting method of exclusively ORing cipher text and key data and decrypting the cipher text, the decrypting method comprising the steps of:

• inputting a synchronization signal, extracting a part of data from the cipher text at the preceding time, and generating key data with the extracted part of the cipher text;
• and
• decrypting the cipher text with the key data.

A computer readable recording medium on which a program that causes a computer to execute a stream cipher decrypting method of exclusively ORing cipher text and key data and decrypting the cipher text has been recorded, the decrypting method comprising the steps of:

• inputting a synchronization signal, extracting a part of data from the cipher text at the preceding time, and generating key data with the extracted part of the cipher text;
• and
• decrypting the cipher text with the key data.