AFAIK this was the concept behind Wuala. Founded in Switzerland, later bought by French company LaCie. According to their website the clien side encryption is still there, however they discontinued the collaborative disk space business model.
We're trying to recreate that concept with peergos, https://github.com/ianopolous/Peergos we're considering trying to use ipfs, http://ipfs.io under the hood which would be nice. Wuala was great but they never open sourced it and stopped the storage earning in 2008.
