I am currently using mac os disc utility on mac and normally create a 10GB encrypted image to store my random private files in...

What really makes me paranoid is how fast or shall we say that it opens instantly once i put in my passcode.

I tried to experiment, made a 50GB encrypted volume, filled it... again it opens scary fast. In comparison when using something like veracrypt opening a 50GB encrypted volume could take minutes!

I even created my own program in "C" and tested every combination of AES modes (CBC,ECB..etc), key sizes... and all of them were only as fast as Veracrypt.

Does anyone have a clue of whats actually going on and why Mac encrypted volumes are 100X faster than any other third party encryption programs. And if there now is some cheeky tricks going on in the background, can we still trust that Mac encrypted volumes from disc utility can be trusted?

  • how did you encrypt it?
    – schroeder
    Mar 6, 2020 at 21:34
  • @schroeder Disc utility -> new image -> mac journaled + aes-256 -> out comes the volume that i use... Now i got a little bit nervous hehe, have i missed a step here?
    – CoffeDev
    Mar 6, 2020 at 21:39
  • 1
    How fast it opens isn't an indication of its security (well, except for how slow the password hash is). It doesn't decrypt the entire volume when you open it, it just decrypts individual blocks as they're read from the image (and encrypts blocks as they're written). Since opening the image and mounting the volume only requires reading some volume data structures (and maybe the top-level directory), it should be pretty quick even for a huge disk image. Mar 6, 2020 at 22:31
  • @GordonDavisson Oh thats interesting, i am going to try to make one single huge file later and see what happens when i try to open it... But i do wonder then why veracrypt would not use the same technique and instead makes us wait for full decryption.
    – CoffeDev
    Mar 6, 2020 at 22:36
  • @GordonDavisson actually i just tried to make an 30 gb file just now, and it really did open pretty much 100X faster than veracrypt again...?
    – CoffeDev
    Mar 6, 2020 at 22:38


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