Force dm-crypt checkbox in "Open partition..."

[mmatuska]

A "force dm-crypt" checkbox in "Open partition..." dialog would give a workaround the problem of not opening LUKS partitions on Windows 7 and 8.

Related to #24

[t-d-k]

These are comments by @mmatuska on this point on a different issue:

I am having the same issue on Windows 7 Pro 64 bit PC I am also not able to dump luks.box or the partition: "Unable to dump out critical data block. ..."

I have some more information on this:

If you open luks.box via "File->Linux Container->Mount file (dm-crypt)" a different key entry box appears ("Librecrypt dm-crypt key entry") and the mount is successful.

If you do the same via "Open file..." or "Open partition..." (for a partition) the "Key Phrase For LUKS Container" entry box appears and the mount does not work ("Unable to open container. Please check your keyphrase and settings, and try again.")

[t-d-k]

When you say it was successful - could you browse the drive after it was opened, and see a file called 'readme.txt'? If you get a prompt to format the drive in windows, and accept it, then this will corrupt the container and it won't afterwards open as a LUKs file. dm-crypt containers do not have a header, so any file can be opened as one, but if it was not created as a dm-crypt container then the results will be garbage.

I have found a relevant bug, namely that a LUKS container will only open if it is writeable, even if opening read-only. This is fixed for the next release. Could you please retest with LUKS.box, after re-downloading the file, and setting the file to writeable? thanks tdk

[t-d-k]

The menu items and dialogs are being reworked in 6.3 to make it clear whether a volume is being opened as a dm-crypt one or LUKS, which should clear some of this confusion.