METHOD AND DEVICE FOR DATA CIPHERING

• Main Authors: KAWAKUBO HIDEJI, TAKADA SHUNSUKE
• Format: Patent
• Language: English
• Published: 09.10.1998
• Edition: 6
• Subjects: ADVERTISING; CODING OR CIPHERING APPARATUS FOR CRYPTOGRAPHIC OR OTHERPURPOSES INVOLVING THE NEED FOR SECRECY; CRYPTOGRAPHY; DISPLAY; EDUCATION; ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; PHYSICS; SEALS; TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHICCOMMUNICATION

PROBLEM TO BE SOLVED: To detach the external device from an information terminal equipment to be carried and to prevent the leakage of a cipher key and the theft and elimination, etc., of cipher data by preserving the ciphered data obtained by generating the cipher key and performing a ciphering/deciphering processing in a set security protection area inside the external device of a computer card or the like. SOLUTION: In the computer card 21, data from the information terminal equipment received by a terminal input/output control part 31 are divided into plural by controlling the entire internal part by the control part 23 of a security protection part 22. A random number generation part 25 generates the cipher key corresponding to the respective divided data by using a generated random number and stores it in a cipher key storage part 27 and the control part 23 retrieves a cipher system storage part 26 and selects a cipher system corresponding to the respective cipher keys. By using the cipher key and the cipher system, a ciphering/deciphering part 24 stores the respective ciphered data to which the ciphering processing is performed in a ciphered data storage part 30 and stores ciphering information used for the deciphering processing in a ciphering information storage part 28. Thus, strength against the cipher decoding of a third person is improved.