. 2021 Jun 28;21(13):4419. doi: 10.3390/s21134419

Table 2.

File filtering process.

Pseudocode 1: Pre-Operation	Pseudocode 2: Post-Operation
Input: application comparison result $F l a g$ , file path $f p a t h$ . Output: preset digest of cipher data $d i g e s t$ . 1 … 2 $v a r p r e f i x = read_file_header (f p a t h);$ 3 if $p r e f i x =' E N C' A N D F l a g = T r u e$ then 4 $v a r d i g e s t = p r e f i x . d i g e s t;$ 5 $v a r p s i z e = p r e f i x . p s i z e;$ 6 $file_read_start_position + = p s i z e;$ 7 End 8 …	Input: preset digest of cipher data $d i g e s t$ , read the file index $f i n d e x$ and the data $f d a t a$ . Output: read file data $f d a t a$ . 1 … 2 $v a r c D a t a = f d a t a;$ 3 $v a r d i g e s t 1 = generate_digest (c D a t a);$ 4 if $d i g e s t 1 = d i g e s t$ then 5 $v a r k e y = get_fileKey (f i n d e x);$ 6 $v a r p D a t a = decrypt (c D a t a, k e y);$ 7 $f d a t a = p D a t a;$ 8 End 9 …

Pseudocode 1: Pre-Operation

Pseudocode 2: Post-Operation

Input: application comparison result

F l a g

, file path

f p a t h

.
Output: preset digest of cipher data

d i g e s t

Input: preset digest of cipher data

d i g e s t

, read the file index

f i n d e x

and the data

f d a t a

.
Output: read file data

f d a t a