| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for generating a closure releasing key for easily preparing a work key safe for security and capable of ensuring safety. SOLUTION: A safe work key is generated from one secret master key KM known to a party at a cypher station A and another party at a cypher station B, and from an additional pair of arbitrarily selected signals. Furthermore, one random number signal RA of a pair of randomly selected random number signals is generated in the random number generation element 10 of the station A, and the other random number signal RB is generated in the random number generation element 20 of the station B. Then, the random number signal RB sent from one party (station B) to the other party (station A) is enciphered in the enciphering element 22 of the station B before transmission, and decoded with the decoding element 13 of the station A after receipt. For the enciphering and decoding processes, a symmetrical key enciphering system using the master key KM, is applied. Then, both of the random number signals RA and RB are interchangeably combined with each other in a combination element 14, thereby forming a work key KS. |
