How to mount and decrypt external drive which has been encrypted by Ubuntu prior?

Problem description:

A couple of years ago I spent a week or so reviewing which backup solution I wanted to go for. Murphy’s law dawned on me once again when I woke up to a laptop that had been pissed on (by myself, dont ask).

I have now opened up the laptop and taken out the drive to connect it to another computer by USB and I can view the folders on the drive. My problem is that I can’t really figure out how to determine which version of LUKS(or whatever) was used to decrypt it, and which terminal tools I need to use to decrypt it so that I can access the content on the machine I have connected it to.

It would be greatly appreciated if anyone could point me in which direction I should go to start troubleshooting or perhaps give me a brief guide on how to do it. My hope is that since the folders are showing up etc., my urine hasn’t reigned complete damage on the drive(pun intended?).

I am not sure if I have posted this in the right category, please move it about if so.

    internetman@internetmachine:~$ df -h
Filesystem                       Size  Used Avail Use% Mounted on
udev                             3,8G     0  3,8G   0% /dev
tmpfs                            771M   18M  753M   3% /run
/dev/mapper/elementary--vg-root  914G   96G  772G  11% /
tmpfs                            3,8G   62M  3,8G   2% /dev/shm
tmpfs                            5,0M  4,0K  5,0M   1% /run/lock
tmpfs                            3,8G     0  3,8G   0% /sys/fs/cgroup
/dev/sda2                        705M  327M  328M  50% /boot
/dev/sda1                        511M  7,3M  504M   2% /boot/efi
tmpfs                            771M   76K  771M   1% /run/user/1000
/dev/sdb1                         19G  9,6G  7,7G  56% /media/internetman/TAILS 1.1.2 - 20140924
/dev/sdb6                         96G   89G  1,5G  99% /media/internetman/TAILS 1.1.2 - 201409241

I guess it’s sdb1 and sdb6 I am interested in mounting+decrypting. The reason it says TAILS is because I installed it once and it has stuck to the bootloader forever for whatever reason.