Searchable Blockchain-Based Healthcare Information Exchange System to Enhance Privacy Preserving and Data Usability

. 2024 Feb 29;24(5):1582. doi: 10.3390/s24051582

Algorithm 2 Block Validation

Require:
New EHR Block, Information of Last Block, Pool of Public Keys ( $P K$ )
Ensure:
Validity of the Block
1:
Step 1: Verify the uniqueness of the new block’s timestamp.
2:
if timestamp of the new block exists within the same timeframe in the chain then
3:
Deny the new block. return Invalid
4:
end if
5:
Step 2: Check if the new block was created after the last block in the chain.
6:
if timestamp of the new block ≤ timestamp of the last block in the chain then
7:
Deny the new block. return Invalid
8:
end if
9:
Step 3: Validate transactions within the block.
10:
for each transaction in the new block do
11:
Step 3.1: Verify the transaction signature using the $P K$ pool.
12:
if signature of the transaction cannot be verified with any $P K$ in the pool then
13:
Deny the new block. return Invalid
14:
end if
15:
Step 3.2: Ensure the transaction is signed by a single user.
16:
if transaction contains signatures from multiple users then
17:
Discard the new block. return Invalid
18:
end if
19:
end for
20:
Step 4: Verify the previous block’s hash value.
21:
if previous hash value in the new block ≠ hash value of the last block in the chain then
22:
Discard the new block. return Invalid
23:
end if
24:
Add the new block to the chain. return Valid