S.1 Subejct $\to$ Service—Provider : N_s; $\underset{M}{\underbrace{\left(S,O,A\right)}},{\left\{H\left(M\right)\right\}}_{k_s^{-1}}$

S.2 Service—Provider $\to$ AC—Contract : N_p, N_s; $\underset{M}{\underbrace{\left(S,O,A\right)}},{\left\{H\left(M\right)\right\}}_{k_s^{-1}}$

S.3 AC—Contract $\to$ Subject : N_c, N_s

S.4 Subject $\to$ AC—Contract : $\underset{N}{\underbrace{N_c,N_s}},{\left\{H\left(N\right)\right\}}_{k_s^{-1}}$

S.5 AC—Contract $\to$ Blockchain : Tx_id, N_p, (S, O, A)

S.6 AC—Contract $\to$ Service—Provider : Tx_id

S.7 Service—Provider $\to$ Blockchain : Tx_id, N_p, (S, O, A)