CoreStorageFamily::unlockVEKs() failed to unwrap the vek, status = e00002bc

I have a filevault2 disk with two partition. One is the boot partition, the other contains data, both are encrypted.

Today, after installing the latest 10.8 update (10.8.4 I guess), the computer reboots, asks for the user password at EFI (filevault2) and starts in verbose mode as usual.

Unfortunately, the boots hangs with a line:

CoreStorageFamily::unlockVEKs() failed to unwrap the vek, status = e00002bc

I can boot in single user mode and execute fsck_cs. The drive appears undamaged (so says fsck_cs) but again, the error message about the-said VEKs is printed on the screen. The second partition, the one that contains the data is the one causing the issue.

What can I do to get back my precious data ?

EDIT: It appears both volumes can be mounted as external disk from an other MAC computer. So, what's with the VEK preventing the system to boot ?

I noticed fsck_hfs running when i get this error.

So i suspect that the volume needed to be fsck'd, and because this sometimes can take longer than the time the authentication is supposed to take, an error got signalled by the authentication dialog, leading to the e00002bc error in the system log.

A look at /var/log/fsck_hfs.log will tell you if this is what happened in your case.

On my 4T external disk the fsck took about 5 hours.