Padding is applied:
./padding 1GB 1GB.ap -a
Padding is removed:
./padding 1GB.ap 1GB.np -r

Padding with encryption:
./padding 1GB 1GB.ap -ea Padding is removed with decryption: ./padding 1GB.ap 1GB.np -dr

sha256sum(33) == sha256sum(33.np)
If the hashes are not equal, something went wrong.

Due to the nature of the RFC5652 specified algorithm, the padding will always be added.

The hash of the in and output files shall be the same,
after adding and removal of the padding.
The execution was not successful on any exit code different than 0.

dd if=/dev/urandom of=1K bs=1K count=1
dd if=/dev/urandom of=1M bs=1M count=1
dd if=/dev/urandom of=253B bs=253 count=1
dd if=/dev/urandom of=256B bs=256 count=1
dd if=/dev/urandom of=257B bs=257 count=1
dd if=/dev/urandom of=1GB bs=1GB count=1