Blockchain-Based Data Access Control and Key Agreement System in IoT Environment

. 2023 May 29;23(11):5173. doi: 10.3390/s23115173

Algorithm 1 PBFT Consensus for Block Addition in Blockchain by Cloud Server

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Input: Block $(B l o c k_{m}$ as shown in Figure 3, transactions pool $(T x_{p} o l)$ , transactions threshold $(T x_{t h r e s h = t}$ , number of $C S$ nodes: $n_{c s}$ , minimal approval $(M i n_{a p p r o v e} = 2 * (n_{c s} - 1) / 3 + 1)$
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Output: Commitment for block addition ( $C M P$ )
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Assume that a cloud server node ( $C S_{l}$ ) is elected as a leader
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$C S_{l}$ picks a fresh timestamp and creates a block $B l o c k_{m}$ with $T x_{p o o l}$
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$C S_{l}$ sets $C M P = N U L L$ and sends $B l o c k_{m}$ to follower cloud server nodes ( $C S_{k}$ $(k \neq l | k = 1, 2, \dots, n_{c s})$ ) for voting request
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for each follower $C S_{j}$ do
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if (( $T x_{j} = v a l i d$ ) and ( $M R = v a l i d$ ) and ( $E C D S A . s i g_{T x} = v a l i d$ ) and ( $C B H a s h = v a l i d$ )) then
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Set $C M P = C M P + 1$
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end if
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end for
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if ( $C M P \geq M i n_{a p p r o v e}$ ) then
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Add $B l o c k_{m}$ to the blockchain
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Broadcast commitment message to $C S$
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end if