Well, I can tell you from personal experience what a MyBook partition table
should look like. I've actually had reason to dick around with one's partition table last week (don't ask). They have a single type 0x07 (HPFS/NTFS) partition starting at CHS 1/0/0 and ending on the last CHS. The partition is pre-formatted with an NTFS filesystem.
The partition table your tools are showing isn't even sane. The secondary partition that supposedly contains the ext3 filesystem starts 100+GB into the disk, and extends beyond both the containing primary partition and the end of the drive itself. You can also tell from the garbled filesystem label that there is no ext3 superblock at that position (well, it's very
unlikely, anyway). Probably a random value of 0x83 just happened to fall at offset 0x04 of one of the 16 partition records. A naive tool will just say "ooh, a partition!" even if everything else in the record is completely nuts.
This guy's blog did a pretty good reverse engineering of the MyBook Essential/Elite encryption system. Suffice to say, the encryption is always on, even if you haven't specifically enabled it or set a password. When you "enable" the encryption with SmartWare, what probably happens is that it encrypts the decryption key(s) using your password so that they can't be automatically decrypted anymore without the password.
The exact details of the encryption system are known only to HP, so we can really only guess at the exact mechanism. They're certainly doing something odd with sector 1 (this should normally be zero-filled), but it isn't clear what. I'd be curious to know what this looks like both in and out of the enclosure when a password has been set. I'd also like to see sectors 2-63. These are also normally unused and should be zero-filled, although some boot loaders will make use of 1-63.
In any case, it's clear from his analysis that both the disk contents and the MBR/partition table are indeed encrypted out-of-the-box and without the user having enabled it/set a password. I wish I had better news, but the bottom line is that you need the USB-to-SATA bridge IC from the enclosure in order to decrypt the disk contents. If you still have any doubts, do a dump of sectors 0-63 and post it here (or at least sector 0). It should be really obvious if the MBR is encrypted. I know this can be done with
HxD, and probably other free tools as well.