BSSPD: A Blockchain-Based Security Sharing Scheme for Personal Data with Fine-Grained Access Control

Algorithm 3

Apply.

 Input: from, pk, nonce

 Output: bool

1 u = account_idx.find(from)

2 ifu != nullthen

3 

  account_idx.modify(u);

4 return true;

5 else

6 

7 ifpow > targetthen

8  return false;

9 else

10  u.A = from;

11  

12  account_idx.emplace(u);

13  return true;

14 end

15 end