lecithine

Lecithine is a FUSE (file system in user space) using a secret sharing scheme.

You can use Lecithine as regular file system.
When writing to disk, data will be devided into randomly chosen pieces (secret shares) and stored into different places. Upon reading, the shares are merged together such that in turn the plaintext results.

From a cryptographers point of view, there is no symmetric or private key ever needed to produce a ciphertext. This is how secret sharing schemes are designed.