par2 is not just for checksumming and recovering Usenet binaries, you can use it for your backups as well.
In my case, I wanted to make sure my RAW and JPG files don't get corrupted by bitrot.
Generating the checksum:
$ cd /the/directory/where/files/are/kept
$ par2 c something.par2 *
$ shasum -a 256 * > shasum256.txt
By default, the checksum files can recover up to 5% of data corruption.
To increase the amount of recovery data, for example by 20%:
$ par2 c -r20 something.par2 *
Verifying the files:
$ cd /the/directory/where/files/are/kept
$ shasum -a 256 -c shasum256.txt
$ par2 v something.par2