	US 12,034,839 B2
	Multi-party session key agreement method
Soonhwa Sung, Daejeon (KR)
Assigned to THE INDUSTRY & ACADEMIC COOPERATION IN CHUNGNAM NATIONAL UNIVERSITY (IAC), Daejeon (KR)
Filed by The Industry & Academic Cooperation in Chungnam National University (IAC), Daejeon (KR)
Filed on Aug. 23, 2022, as Appl. No. 17/893,743.
Claims priority of application No. 10-2022-0059493 (KR), filed on May 16, 2022.
Prior Publication US 2023/0370250 A1, Nov. 16, 2023
Int. Cl. H04L 9/08 (2006.01)

CPC H04L 9/0833 (2013.01) [H04L 9/0838 (2013.01)]

6 Claims

1. A multi-party session key agreement method comprising:

a test session for exchanging a short-term key between parties of 3 to n peers; and

an original session for exchanging a long-term key between the parties who have exchanged the short-term key,

wherein Â possess a long-term key pair (a, A), B possess a long-term key pair (b, B), and Ĉ possess a long-term key pair (c, C), and the test session includes the sub-steps of:

(a) activating session s=(Â, i), selecting a short-term private key, calculating X=g^fI(rÂ,a,Ω), and sending X to B and Ĉ by Â;

(b) activating session s=(B, i), selecting a short-term private key, and calculating Y=g^fR(rB,b,Ω)and K_B=F_R(f_R(r_B,b,Ω),b,X,Ω) by B;

(c) activating session s=(Ĉ, i), selecting a short-term private key, and calculating Z=g^fR(rĈ,c,Ω)and K_Ĉ=F_R(f_R(r_Ĉ,c,Ω),c,Y,Ω) by Ĉ;

(d) sending Y to Â by B, and sending X and Y to Ĉ by Â;

(e) sending X and Z to B by Ĉ, and sending Y and Z to Â by B;

(f) completing the session using session key K_Bby B after confirming X;

(g) completing the session using session key K_Ĉby Ĉ after confirming Y;

(h) calculating K_Â=F_I(f_I(r_Â,a,Ω),a,Y,Ω) by Â after confirming Y;

(i) completing the session using session key K_Âby Â after confirming Z; and

(j) confirming whether H(session key value+transaction session key tree root value)<TV (Target Value), and conducting the original session step if satisfied, and terminating the session if not satisfied, by Â, B, and Ĉ, respectively,

where Â, B, and Ĉ are party A, B, C respectively, where X, Y, and Z are short-termed public keys of the party A, B, and C respectively, where rÂ, rB, and rĈ are short-term private keys of party A, B, C and respectively, where K_Â, K_B, and K_Ĉare session keys of party A, B, and C respectively, where A, B, and C are long-term public keys of party A, B, and C(A=g^a), (B=g^b), and (C=g^c) respectively, where a, b, are c are long-term private keys of party Â,B, and Ĉ (a∈z_p) respectively, where pK_Â, pK_B, and pK_Ĉare agreement public keys of party Â,B, and Ĉ respectively, where sK_Â, sK_B, and sK_Ĉare agreement private keys of party Â,B, and Ĉ respectively, and, where g is a generator.