I want to create a bit-by-bit backup of my DVD and a Blu-ray disc without removing its encryption. Is dd be the best method, and if so, what flags or settings should I use? Also, is comparing the SHA-256 hash of the generated ISO file with the hash of the original disc’s raw data (read from /dev/sr0) the best method for verifying the backup’s integrity?
There are layers below the bits. Writable CDs are made from different chemicals, so it’s obvious they are copies. Heck, some of them are obviously different colours, like blue.