Idea is to identify pieces of data by the hash-id of the data.

This can be implemented very easily on a key-value store. To store data x, compute hash(x) and store in key-value store using hash(x) as key.

A bit more work is required to do this securely.

vs. location-addressed

Content on the Web is usually location-addressed. That is the identifier of the data is a location of a host serving the content. This causes problems with content Availability.

See also

The web of names, hashes and UUIDs

An article by Joe Armstrong describing how content-addressed storage is part of his plan of "reversing entropy".

Principles of Content Addressing

IPFS

A content-addressable storage. Does not do any securing of content.