The obvious answer to this question is not so clear as one would expect.
Surely encryption procedures are really useful if you want to prevent your precious and sensitive data from being accessed by other people.
On the other side of the medal, you must ask yourself: what will happen in the event a problem occurs with the storage device.
Nowadays, there are many common schemes providing on the fly encryptions for the whole drive or, as per the oldest ones, for chosen directories only: some of them are embedded in the Operating System, totally transparent to the user. You will notice the software only the first time the encryption is launched (usually at the Operating System installation), asking to create a password.
Well in the case of problems at the storage device, not only hardware but logical ones too, many times the data cannot be accessed only because the encryption software cannot read just a few sectors, usually and sadly the ones that you cant recover…
The software is doing the work at its best: it is blocking the access to the data until everything will be fine according to its standard, in order to start the decryption.
A good example comes from a job we had last week: a notebook was dropped and its internal drive stopped working, because of damaged due to this event. Customer warned us that he had enabled the “Lion File Vault” encryption… We managed to fix the hardware faults and start cloning the drive sector by sector. The surfaces were damaged by the original mangled heads: many scratches meant many unreadable sectors, just because the magnetic layer has been stripped away. So, the result was that the clone of the original drive, even successfully created, suffered from many “blank” sectors: the MAC couldnt recognize it and so the decryption procedure couldnt be applied at all…
No worries: we used our specialized software tool that could start the decryption process on the defined data area and reconstruct the file system structures. Data was recovered and, as not expected, the damaged files resulted to be very little in number.
Thanks to this tool we can, at the moment, offer support with devices and partitions encrypted by Windows Bitlocker, Apple FileVault and TrueCrypt. Beware: this tool is not intended to break or hack an encryption by some brute-force method (an attempt that would be almost impossible anyway…). It simulates a decryption process as it is performed in original utility using customers Password or the key-file that encryption utilities create when the user switches on the encryption option.