sigbak is a command-line utility to read the encrypted backups created by the Signal messaging app. It can be used to extract messages and other data.
Documentation is available in the manual page.
This repository contains sigbak-portable, a portable version of sigbak. sigbak proper currently builds on OpenBSD only. sigbak-portable adds a portability layer so that it will build on other Unix systems.
sigbak-portable depends on libcrypto (from either LibreSSL >= 2.6.0 or OpenSSL >= 1.1.0), protobuf-c and SQLite. A C compiler, make and pkg-config are also needed.
On Debian-based distros it should suffice to install the following packages: build-essential libprotobuf-c-dev libsqlite3-dev libssl-dev pkg-config protobuf-c-compiler.
First check if config.h is suited to your system. Edit it if necessary. config.h already has support for several systems. On those systems, no editing should be necessary.
Then run make and, if desired, make install.