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Extremely quick mount in Linux version?

Topics: Technical Issues
Sep 21, 2016 at 7:08 PM
Maybe I did not understand well the docs, but mounting on linux behaves really strange. Looks like the VeraCrypt on Linux doesn't use the PIM (?) or is using some backdoor.

At first the setup of my test:
  • Very old laptop, i7-m620, 8GB RAM, 2 physical disks.
  • Disk 1: 1 partition, Windows 7 64 bit, system encryption, VeraCrypt bootloader.
  • Disk 2: first 2 partitions (unencrypted): Ubuntu 16.04 64 bit + swap, third one is whole encrypted NTFS also with VeraCrypt.
  • Booting from disk 1 or disk 2 is controlled by BIOS.
  • I am not using PIM, so it means I am using default PIM.
From Linux I am often using those two encrypted partitions - system disk 1 and nonsystem partiton from disk 2.

There are significantly different mounting times from those systems!

System drive encrypted mount
  • VeraCrypt Bootloader (16bit) + pass OK: 33.20 s
  • Ubuntu 16.04 (64bit) + pass OK: 3.66 s (!!!!!)
  • VeraCrypt Bootloader (16bit) + pass BAD: 32,90 s
  • Ubuntu 16.04 (64bit) + pass BAD: 22.02 s
Nonsystem drive encrypted mount
  • Windows 7 (64bit) + pass OK: 10.62 s
  • Ubuntu 16.04 (64bit) + pass OK: 3.37 s (!!!!!!)
  • Windows 7 (64bit) + pass BAD: 33.73 s
  • Ubuntu 16.04 (64bit) + pass BAD: 56.28 s (!!!!!)
Times are average from several tests.

I am OK with boot mounting to Windows (system drive encryption) about 30 seconds. But what the heck with linux - it can mount the same drive in about 3 seconds??? And on the other side - bad password for nonsystem drive means about 30 seconds of waiting on Windows while on linux it is almost one minute.

Looks like the linux version of VeraCrypt is working differently with PIM (maybe). I cannot say, if I am sad that the Windows version cannot use this method or I am sad that this method exists...
Sep 21, 2016 at 8:45 PM
This is a joke of multi threading and order of hash to check.

The following facts:
  1. Windows uses several threads to mount.
  2. Linux uses one thread.
  3. Hash check order and speed: SHA-512(~200MB/s), Whirlpool(~85MB/s), SHA-256(150MB/s), RIPEMD-160(150Mb/s), Streebog (70MB/s)