KEY MANAGEMENT METHOD

• Main Authors: TAKASHIMA YOICHI, KANDA MASASUKI
• Format: Patent
• Language: English
• Published: 13.10.1998
• Edition: 6
• Subjects: ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHICCOMMUNICATION

PROBLEM TO BE SOLVED: To attain decoding of an encrypted text and copy of a session key within a range decided by a certification agency only. SOLUTION: The management method divides system secret information Rs into (Rs1 , rs1 ), (Rs2 , rs2 ) (Rs =Rs1 +Rs2 =rs1 .rs2 ) and the result is stored in an agency 3, secret information Si of a user (i) is divided into Si1 , Si2 , which are stored in the agency 3, and user public information Pi =g mod p is open to the public. A user 1 sets a key KS to generate a key Kab =Pb and uses date time information D to generate a key Kd =Kab .g .D, encrypts the KS and sends it to user 2. The user 2 obtains the Kab , Kd , decodes the encrypted KS to obtain the KS. When an agency 5 decodes an encrypted text, the agency c5 submits a certificate to the agency 3, and when the certificate is valid, the agency 3 generates K1 (K2 )=Pb S /rs1 mod p and sends it to the agency 5, the agency 5 obtains K'=K1 .K2 and sends it to the agency 3. The agency 3 calculates K1 ' (K2 ')=Pb S .g '.D.R (mod p) and sends it to the agency 5, and the agency 5 obtains the KS from Kd =K1 '.K2 '.