libchop, tools & library for data backup and distributed storage

Libchop is a set of utilities and library for data backup and distributed storage. Its main application is chop-backup, an encrypted backup program with several salient features:

Read more…

The library itself was initially designed as a building block for a peer-to-peer, cooperative backup system. In such a system, data has to be sent by pieces, incrementally, and it may be scattered across several participating nodes. In addition, participating nodes may be untrusted, which puts data confidentiality, integrity, and availability at risk. Read more…

Libchop was initially developed as part of a PhD thesis in the MoSAIC project.


Releases are available from your nearest Savannah mirror (or from Savannah itself).


Mailing List

A mailing list for bug reports and general discussion is available at <>. You can subscribe to the mailing list and view the list archive.


Related Work

  • Plan 9's Venti provides unencrypted content-addressable storage and archival.
  • GNUnet uses content-hash keys for its file sharing service (like chop-backup). Some of the early papers on its data encoding scheme (ECRS) were instrumental in the design of parts of libchop and chop-backup.
  • Tahoe-LAFS is a distributed file system, where data is encrypted but remains selectively shareable; it handles redundancy automatically. It has a backup sub-command.
  • Ugarit, a nice content-addressable backup & archival system written in Chicken Scheme. The main differences compared to chop-backup are that it does not use content-hash keys for encryption (a symmetric encryption key must be kept in a ugarit.conf file), and lacks adaptive compression and content-based chopping (it doesn't implement the storage pipeline found in libchop.)

Validate XHTML 1.0