Privacy-Preserving Outsourced Auditing Scheme for Dynamic Data Storage in Cloud

Algorithm 2

Algorithm for deleting a block.

Algorithm: Delete_Block  .

Input: the location of the appointed block that will be deleted.

Output: the new of the updated MHT.

User: transmit to CSP;

CSP: based on , read and from its MHT ;

send to user;

User: compute ;

if then

authorize CSP to execute delete operation;

end if

CSP: if the sibling node of , denoted by , is a leaf node then

replace with the parent node of which is transformed into a leaf node, and then delete from MHT ;

else

replace with the parent node of , and delete from MHT ;

end if

update the MHT stored in cloud by recalculating all the nodes on the path from

to the new root of MHT , denoted by ;

delete , from the outsourced file , and send to user;

User: set ;

compute ;

if then

transmit () to TPA;

end if

TPA: update the MHT stored at TPA side by the same way as CSP;

send to user the root of the updated MHT , denoted by ;

User: if then

update the , stored in her local, with ;

end if

return ;