Hmm... Well, I wasn't using encryption, but I did migrate successfully from OC 9.0.2 > NC 9.0.51.
All I had to do was:
- Put OC into offline mode with occ
- Change the root folder name of OC
- extract the zip file of NC that I downloaded from the NC website.
- Copy over the config and data folders (well, actually just config for me, as my data folder was already external)
- Use occ's upgrade command.
For more detailed instructions though, see the migrating link posted above in the previous post.