Key distribution method.

摘要

The invention relates to a method of distributing a key for enciphering un unenciphered or plaintext message and for deciphering the enciphered message. The method comprises the following steps: generating a first random number in a first system (101); generating first key distribution information in the first system (101) by applying a predetermined first transformation to the first random number on the basis of first secret information known only by the first system (101); transmitting the first key distribution information to a second system (102) via a communication channel (103); receiving the first key distribution information in the second system (102); generating a second random number in the second system (102); generating second key distribution information by applying the predetermined first transformation to the second random number on the basis of second secret information known only by the second system (102); transmitting the second key distribution information to the first system (101) via the channel (103); receiving the second key distribution information in the first system (101); and generating an enciphering key in the first system (101) by applying a predetermined second transformation to the second key distribution information on the basis of the first random number and identification information of the second system (102) which is not secret.