Quite some time ago I've noticed that even if I create DMG files from the same directory, with same files and etc, the results are always different. Not only their size is ~15 bytes shorter/longer from one another, but their SHA checksums (and their contents, when being viewed from the HEX editor) differ drastically. Just out of curiosity, I've created 5 compressed unencrypted DMG files from the same folder containing nothing but a single text file. The results are:
- 0.dmg | size - 26 204 bytes, checksum - 5ba9ba0ee4d8ec5ba4718f1b491baf31c2c4e642
- 1.dmg | size - 26 221 bytes, checksum - a86d76f6c07ee5a81c0aefb31b6fd40ef787ebd5
- 2.dmg | size - 26 235 bytes, checksum - a31f4cf29e4e2858b7ac63c82574499200d81108
- 3.dmg | size - 26 209 bytes, checksum - f3c19414279b6d6b94b90341453906e4a69e28dd
- 4.dmg | size - 26 217 bytes, checksum - 9603c0334125762fc7908343e3ee400e038fe779
I've been browsing the internet hoping to find anything about the "data randomizer in APFS", but... obviously couldn't find a single thing, and in addition, not a lot of people actually knew about this "feature". Is there any info about it?
I'm running macOS 10.12.6, the DMG files were created using Disk Utility, but I get the same results with hdiutil.