Salvage distributes sensitive data to multiple people such that it can only be recovered by several people working together. This is useful for storing information with both a low risk of losing access to it and a low risk of accidental disclosure. A classic application is to create a "recovery kit" for a server or infrastructure, which can be used in the event that conventionally stored keys and credentials become lost or unavailable.
Salvage works by encrypting a file or directory with a random master key and then applying a simple key-splitting scheme to distribute the key across multiple shares. You can create a kit for any number of participants with any threshold required to recover the information. For example, you might create a kit for five people, any three of whom may combine their shares to recover the data.
Salvage runs under Python 2.7 or Python 3.2 and later. The only external dependency is gpg, for the cryptography. For maximum utility, it is packaged as a single flat Python script that can be run with no installation. The algorithms and file formats are simple and carefully documented to ensure that recovery is always possible even if this software is unavailable for some reason.
$ pip install salvage
This package will only install the salvage executable. It does not depend on
any Python packages.
To create a new salvage kit for five participants with a recovery threshold of three:
% salvage new 5 3 path/to/source/dir
This will create five shares, each containing an encrypted archive and some metadata. To decrypt and unpack the archive:
% salvage recover path/to/share1 path/to/share2 path/to/share3
The three paths must be three of the shares generated in the first step. The master key will be reconstructed and the data will be decrypted and unpacked.
See salvage -h for additional options.