Algorithm 2 Blockchain layer algorithm for secure east–west communication

Require: East–west control packets ${\mathcal{R}}_C^t$, controller set $\{C_1,C_2,\dots ,C_n\}$ Ensure: Verified block $B_{verified}$, access control decision ${\mathcal{A}}_{ctrl}$   1: for all controller $C_i\in \{C_1,C_2,\dots ,C_n\}$ do   2:     Collect trust communication packets $r_k^t$   3:     Form control data block ${\mathcal{R}}_C^t=\{r_1^t,r_2^t,\dots ,r_p^t\}$   4:     Compute hash ${\mathcal{H}}_{blk}=\mathrm{Hash}({\mathcal{R}}_C^t \Vert S{K}_i)$   5:     Store ${\mathcal{H}}_{blk}$ for block verification   6: end for   7: PoA Validator Selection   8: for all interested controller $C_i$ do   9:     Compute reputation score ${\rho }_i$ and transaction history ${\tau }_i$   10:   Compute selection probability:           ${\mathbb{P}}_{auth}\left(C_i\right)={\displaystyle \frac{{\omega }_1·{\rho }_i+{\omega }_2·{\tau }_i}{{\sum }_{j=1}^q({\omega }_1·{\rho }_j+{\omega }_2·{\tau }_j)}}$   11: end for   12: Select top-v validators based on ${\mathbb{P}}_{auth}\left(C_i\right)$   13: Consensus Voting   14: for all validator $C_k$ do   15:    Verify transaction set T   16:    Cast vote $v_k\in \{0,1\}$   17: end for   18: Compute total approvals: $V_{yes}={\sum }_{k=1}^v{v}_k$   19: if $V_{yes}\ge {\theta }_{cons}$ then   20:    Compute commit hash $H_{commit}=H(T \Vert {\mathsf{\Sigma }}_v)$   21:    Form $B_{verified}$ and append to blockchain   22: else   23:    Discard block and log failure   24: end if   25: IPFS Storage Integration   26: Compute IPFS hash: ${\mathcal{H}}_{IPFS}=\mathrm{Hash}\left({\mathcal{R}}_C^t\right)\to \mathrm{IPFS}$   27: Split ${\mathcal{R}}_C^t$ into chunks ${\mathsf{\Pi }}_k\in {\mathbb{N}}_{IPFS}$   28: ${\mathcal{D}}_{C_i}={\bigcup }_{k=1}^w{\mathsf{\Pi }}_k$   29: Store ${\mathsf{\Pi }}_k$ on distributed IPFS nodes   30: Data Retrieval and Integrity Check   31: Controller sends retrieval request with ${\mathcal{H}}_{IPFS}$   32: IPFS collects ${\mathsf{\Pi }}_k$, aggregates data and returns   33: Controller computes verification hash: ${\mathcal{H}}_{verify}=\mathrm{Hash}\left({\sum }_{k=1}^w{\mathsf{\Pi }}_k\right)$   34: if  ${\mathcal{H}}_{verify}={\mathcal{H}}_{IPFS}$  then   35:     Send acknowledgment and continue   36: else   37:     Trigger arbitration process via smart contract   38: end if   39: Access Control via Signature Validation   40: for all access requests by $C_i$ or federated nodes do   41:     Verify $\mathrm{Sig}\left(P{K}_{node}\right)$   42:     if $\mathrm{Sig}\left(P{K}_{node}\right)$ is valid then   43:         Set ${\mathcal{A}}_{ctrl}\leftarrow 1$   44:     else   45:         Set ${\mathcal{A}}_{ctrl}\leftarrow 0$   46:     end if   47: end for