Patent ID: 7899183

Claim:
A random number generating and sharing system for generating and sharing a random number between a sender terminal and a recipient terminal, comprising: a first generating means, which generates a first random number for said sender terminal; a second generating means, which generates a second random number for said recipient terminal, wherein said second random number is base information; a third generating means, which generates a third random number for said sender terminal, wherein said third random number is base information; generating means which generates a fourth random number based on said second and third random numbers wherein said fourth random number is a part of said first random numbers; holding means for holding said first to fourth random numbers; sending means for sharing said second or third random number with said sender terminal and said recipient terminal; generating and sharing means for generating and sharing encryption key data based on said first to fourth random numbers, holding means for holding said encryption key data, wherein if said sender terminal and said recipient terminal which have been disconnected are connected again to each other, each of said sender terminal and said recipient terminal authenticate each other by confirming a part of said encryption key data held by said holding means for holding said encryption key data, and wherein said second or third random number that is shared by the sending means is shared between said sender terminal and said recipient terminal prior to said sender terminal and said recipient terminal being disconnected.