signal-back

Since version 4.17.5, the Signal Android app encrypts its backup files. While these are undoubtedly a security benefit over unencrypted backups, they do present an issue in being read into other systems or simply by their owner.

signal-back can extract and format the contents of such backup files. You need to specify the file's password; signal-back makes no attempt to figure out the password itself.

Usage

Either build from source or download a pre-built binary and put the executable somewhere you can find it.

Usage: signal-back COMMAND [OPTION...] BACKUPFILE

  --help, -h     show help
  --version, -v  print the version

Commands:
  analyse  Information about the backup file
  extract  Decrypt contents into individual files
  format   Export messages from a signal database
  help     Shows a list of commands or help for one command

Supported export formats are:

XML: Compatible with SMS Backup & Restore
CSV: Comma-Separated Value text file
JSON: JavaScript Object Notation file

Password

The password you need to decrypt the content of the Signal backup file was shown to you by Signal when you enabled local backups similar to this screenshot. It consists of six groups of five digits.

The most secure way to provide the password to signal-back is to enter it in the interactive dialog such as 12345 12345 12345 12345 12345 12345. Your entry will not be echoed to the console nor stored anywhere.

For convenience, if you prefer, you can also provide the password on the command line using -p 12345 12345 12345 12345 12345 12345 or you can write it in a text file and pass it to signal-back using -P password.txt.

Example usage

Download whichever binary suits your system from the releases page; Windows, Mac OS (darwin), or Linux, and 32-bit (386) or 64-bit (amd64). Checksums are provided to verify file integrity.

Find where you downloaded the file and open an interactive shell (Command Prompt, Terminal.app, gnome-terminal, etc.). Make sure your signal-XXX.backup file is in the same folder, or else specify the full path your backup file when running the program.

Extracting

All messages are stored in a sqlite3 database file. Attachment files such as images, videos, and PDFs will be placed in a subfolder named Attachments.

If you're on Windows:

signal-back_windows_amd64.exe extract -o folder signal-XXX.backup

If you're on MacOS or Linux (where e.g., OS is darwin and ARCH is amd64):

chmod +x signal-back_OS_ARCH
./signal-back_OS_ARCH extract -o folder signal-XXX.backup

Enter your 30-digit password at the prompt (with or without spaces, doesn't matter). Note that your password will not be echoed back to you for security purposes.

Everything will be in folder you specified, or if you omitted the -o option, in the folder where you ran the command. Note that some attachments may have a .unknown extension; this is because signal-back might not be able to determine what type of files these are. Please report an issue on github if you encounter one of these.

Importing to SMS Backup & Restore

Once you have extracted the message database, you can convert them into a format usable by SMS Backup & Restore.

If you're on Windows:

signal-back_windows_amd64.exe format -f XML -o backup.xml signal.db

If you're on MacOS or Linux (where e.g., OS is darwin and ARCH is amd64):

chmod +x signal-back_OS_ARCH
./signal-back_OS_ARCH format -f XML -o backup.xml signal.db

You can then copy backup.xml to your phone and restore it using SMS Backup & Restore.

Building from source

Building requires Go and dep. If you don't have one (or both) of these tools, instructions should be easy to find. After you've initialised everything:

$ git clone https://github.com/sean-gugler/signal-back $GOPATH/src/github.com/sean-gugler/signal-back
$ cd $GOPATH/src/github.com/xeals/signal-back
$ dep ensure
$ go build .

You can also just use go get github.com/sean-gugler/signal-back, but I provide no guarantees on dependency compatibility.

Todo list

License

Licensed under the Apache License, Version 2.0 (LICENSE or http://www.apache.org/licenses/LICENSE-2.0).

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be licensed as above, without any additional terms or conditions.

bentolor/signal-back