horcrux

README

horcrux v1.2.4

Split file into encrypted horcrux-files, reconstructable without key

• Repo: https://github.com/pepa65/horcrux
• After https://github.com/jesseduffield/horcrux
• The technique used is Hashicorp's Shamir's secret sharing, based on 256 bit AES encryption with CTR. When not all split parts are required to reconstruct, every part contains the data for the whole file, but only part of the needed key to decrypt it! In case all parts are required, the original file data is split up too. It is possible to only require 1 part for decryption, but in that case only the horcrux binary and 1 file is needed..!
• Versions of horcrux before 1.0.0 (0.5.2 and below) used OFB, are less secure and should no longer be used. Version 1.0.0 and higher use CTR and a different horcrux-file format.

Function

The program horcrux can split a file into a predefined number of encrypted horcrux-files, and reconstruct an original file from a (predefinable) sufficient number of horcrux-files in a directory.

Split

To split up a file into horcrux-files, call horcrux with the filename and optionally flags -n/--number with the number of desired horcrux-files and/or -m/--minimum followed by the minimum number of horcrux-files needed to reconstruct the original file. Example:

horcrux -n 5 -m 3 secret.txt

The resulting horcrux-files can be renamed, dispersed (given to different people or stored at different locations) and later be used to reconstruct the original file if the minimum number of needed horcrux-files are present (in this case: 3 out of the 5 are needed).

Reconstruct

To merge horcrux-files back into the original file, call horcrux in the directory containing the horcrux-files (.yml, or in the case of horcrux --zstd: .horcrux). Alternatively, that directory can be given as an argument: horcrux directory/with/horcrux-files

All other files with non-matching names will be ignored. There should not be any horcrux-files with the same extention in that same directory that were produced with a different command!

Query

To display information about a horcrux-file, call horcrux with the -q/--query flag followed by the filename of the horcrux-file, like:

horcrux -q file.horcrux

Horcrux files ending in .yml can also just be opened as a text file to see all information about them.

Installation

Download

Download any of horcrux horcrux_pi horcrux_bsd horcrux_osx horcrux.exe through:

wget -O BINARY https://gitlab.com/pepa65/horcrux/-/jobs/artifacts/master/raw/BINARY?job=building

(replace BINARY with the desired binary name, e.g. `horcrux is for Linux amd64).

Then put it into a location on your PATH, or use it by specifying its path, like: ./horcrux

Go install

Or do go install github.com/pepa65/horcrux@latest (needs Golang fully installed).

Git clone and go install

Or, clone this repo by: git clone https://github.com/pepa65/horcrux and do cd horcrux followed by go install (needs both Git and Golang).

Better binaries

CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go install -ldflags="-s -w"
CGO_ENABLED=0 GOOS=linux GOARCH=arm go install -ldflags="-s -w" -o horcrux_pi
CGO_ENABLED=0 GOOS=freebsd GOARCH=amd64 go install -ldflags="-s -w" -o horcrux_freebsd
CGO_ENABLED=0 GOOS=darwin GOARCH=amd64 go install -ldflags="-s -w" -o horcrux_osx
CGO_ENABLED=0 GOOS=windows GOARCH=amd64 go install -ldflags="-s -w" -o horcrux.exe

More extreme shrinking

upx --best --lzma horcrux

(Needs upx or upx-ucl installed.)

Usage

horcrux v1.2.4 - Split file into 'horcrux-files', reconstructable without key
Usage:
- Split:  horcrux [-f|--force] [-z|--zstd] [-n|--number N] [-m|--min M] FILE
  -f/--force:  Created horcrux-files will overwrite existing files
  -z/--zstd:   Work with compressed .horcrux files instead of with .yml files
    N:     Number of horcrux-files to produce [1..255, default: 2]
    M:     Min.number of horcrux-files needed to reconstruct [1..N, default: N]
    FILE:  Original file to split up and encrypt
- Reconstruct file:  horcrux [-z|--zstd] [DIR]
    DIR:  Directory with horcrux-files to reconstruct [default: current]
- Query horcrux-file:  horcrux -q|--query FILE
    FILE:  Horcrux-file to query for information (.yml files can be viewed too)
- Get help or version:  horcrux -h|--help | -V|--version