Backing up keys while encrypting

[Anonymous]

I want to make a copy of the part of the header that contains the mouse-generated keys while the encryption process is deferred, so I can access the drive with the password if it is corrupted.

I'm encrypting a 5 TB drive that's almost full, so I couldn't make a backup before (there's nowhere to store all the data) and it would take days to decrypt what's already encrypted.

I have a few more questions: if I accidentally remove the hard drive while encrypting, will the volume header and keys be corrupted or will I only lose the file that was currently being encrypted? What if the laptop goes into hibernation without pausing or deferring the encryption process?

Thanks in advance!

[Mounir IDRASSI]

The volume header contains information about the data encrypted on the disk and these values keep changing while the encrytion is ongoing. So, if we offer to backup the header before the encryption is finished (for example at 10% of the process) and then you continue the encryption process and later the process is somehow aborted at 70% : if you restore the backup created at 50%, then VeraCrypt will think that the encryption stopped at 10% of the disk while in reality it stopped at 70 % and you will end up with losing 60 % of the data.

For these reasons, we strongly recommend to create a backup before encryption data in-place since in-place encryption is very sensitive to issues like power failures.

In case of power failure or unexpected shutdown, the in-place encryption process can be resumed but certainly the volume header will not contain correct information about the actual offset of the last encrypted sector, which means that after resuming the process, some sectors will be wrongly encrypted twice making them unreadable afterwards. Nevertheless, the rest of the disk will be OK and it can be used normally.