Synopsis

Intro

There’s a known problem in server configuration and deploying, when you have to store your private data such as: database passwords, application secret-keys, OAuth secret keys and so on, outside of the git repository. Even if this repository is private, it is a security risk to just publish them into the world wide web. What are the drawbacks of storing them separately?

These files are not version controlled. Filenames change, locations change, passwords change from time to time, some new information appears, other is removed. And you can not tell for sure which version of the configuration file was used with each commit. When building the automated deployment system there will be one extra step: download and place these secret-configuration files where they need to be. So you have to maintain an extra secure server, where everything is stored.

How does git-secret solve these problems?

git-secret encrypts files and stores them inside the git repository, so you will have all the changes for every commit. git-secret doesn’t require any other deploy operations rather than git secret reveal , so it will automatically decrypt all the required files.

What is git-secret ?

git-secret is a bash tool to store your private data inside a git repo. How’s that? Basically, it just encrypts, using gpg , the tracked files with the public keys of all the users that you trust. So everyone of them can decrypt these files using only their personal secret key. Why deal with all this private-public keys stuff? Well, to make it easier for everyone to manage access rights. There are no passwords that change. When someone is out - just delete their public key, reencrypt the files, and they won’t be able to decrypt secrets anymore.

git-secret - bash tool to store private data inside a git repo.

Usage: Setting up git-secret in a repository

These steps cover the basic process of using git-secret :

Before starting, make sure you have created a gpg RSA key-pair: a public and a secret key identified by your email address. Begin with an existing or new git repository. You’ll use the ‘git secret’ commands to add the keyrings and information to make git-secret hide and reveal files in this repository. Initialize the git-secret repository by running git secret init command. The .gitsecret/ folder will be created. Note all the contents of the .gitsecret/ folder should be checked in, /except/ the random_seed file. In other words, of all the files in .gitsecret/ , only the random_seed file should be mentioned in your .gitignore file. By default, git secret init will add the file .gitsecret/keys/random_seed to your .gitignore file. Add the first user to the git-secret repo keyring by running git secret tell your@gpg.email . Now it’s time to add files you wish to encrypt inside the git-secret repository. This can be done by running git secret add <filenames...> command. Make sure these files are ignored by mentions in .gitignore , otherwise git-secret won’t allow you to add them, as these files could be stored unencrypted. In the default configuration, git-secret add will automatically add the unencrypted versions of the files to .gitignore for you. When done, run git secret hide to encrypt all files which you have added by the git secret add command. The data will be encrypted with the public-keys described by the git secret tell command. After using git secret hide to encrypt your data, it is safe to commit your changes. NOTE: It’s recommended to add the git secret hide command to your pre-commit hook, so you won’t miss any changes. Later you can decrypt files with the git secret reveal command, or just print their contents to stdout with the git secret cat command. If you used a password on your GPG key (always recommended), it will ask you for your password. And you’re done!

Usage: Adding someone to a repository using git-secret

Get their gpg public-key. You won’t need their secret key. Import this key into your gpg keyring (in ~/.gnupg or similar) by running gpg --import KEY_NAME.txt Now add this person to your secrets repo by running git secret tell persons@email.id (this will be the email address associated with the public key) The newly added user cannot yet read the encrypted files. Now, re-encrypt the files using git secret reveal; git secret hide -d , and then commit and push the newly encrypted files. (The -d options deletes the unencrypted file after re-encrypting it). Now the newly added user will be able to decrypt the files in the repo using git-secret reveal .

Note that it is possible to add yourself to the git-secret repo without decrypting existing files. It will be possible to decrypt them after re-encrypting them with the new keyring. So, if you don’t want unexpected keys added, you can configure some server-side security policy with the pre-receive hook.

Using gpg

You can follow a quick gpg tutorial at devdungeon. Here are the most useful commands to get started:

To generate a RSA key-pair, run:

gpg --gen-key

To export your public key, run:

gpg --export your.email@address.com --armor > public-key.gpg

To import the public key of someone else (to share the secret with them for instance), run:

gpg --import public-key.gpg

To make sure you get the original public keys of the indicated persons, be sure to use a secure channel to transfer it, or use a service you trust, preferably one that uses encryption such as Keybase, to retrieve their public key. Otherwise you could grant the wrong person access to your secrets by mistake!

Using git-secret for Continuous Integration / Continuous Deployment (CI/CD)

When using git-secret for CI/CD, you get the benefit that any deployment is necessarily done with the correct configuration, since it is collocated with the changes in your code.

One way of doing it is the following:

create a gpg key for your CI/CD environment. You can chose any name and email address you want: for instance MyApp CodeShip <myapp@codeship.com> if your app is called MyApp and your CI/CD provider is CodeShip. It is easier not to define a password for that key. run gpg --export-secret-key myapp@codeship.com --armor to get your private key value Create an env var on your CI/CD server GPG_PRIVATE_KEY and assign it the private key value. Then write your Continuous Deployment build script. For instance:

# Install git-secret (https://git-secret.io/installation), for instance, for debian: echo "deb https://dl.bintray.com/sobolevn/deb git-secret main" | sudo tee -a /etc/apt/sources.list wget -qO - https://api.bintray.com/users/sobolevn/keys/gpg/public.key | sudo apt-key add - sudo apt-get update && sudo apt-get install git-secret # Create private key file echo $GPG_PRIVATE_KEY > ./private_key.gpg # Import private key gpg --import ./private_key.gpg # Reveal secrets git secret reveal # carry on with your build script, secret files are available ...

Note: your CI/CD might not allow you to create a multiline value. In that case, you can export it on one line with

gpg --export-secret-key myapp@codeship.com --armor | tr '

' ','

You can then create your private key file with:

echo $GPG_PRIVATE_KEY | tr ',' '

' > ./private_key.gpg

Environment Variables and Configuration

You can configure the version of gpg used, or the extension your encrypted files use, to suit your workflow better. To do so, just set the required variable to the value you need. This can be done in your shell environment file or with each git-secret command. See below, or the man page of git-secret for an explanation of the environment variables git-secret uses.

The settings available to be changed are:

$SECRETS_VERBOSE - sets the verbose flag to on for all git-secret commands; is identical to using -v on each command that supports it.

$SECRETS_GPG_COMMAND - sets the gpg alternatives, defaults to gpg . It can be changed to gpg , gpg2 , pgp , /usr/local/gpg or any other value. After doing so rerun the tests to be sure that it won’t break anything. Tested to be working with: gpg , gpg2 .

$SECRETS_EXTENSION - sets the secret files extension, defaults to .secret . It can be changed to any valid file extension.

$SECRETS_DIR - sets the directory where git-secret stores its files, defaults to .gitsecret. It can be changed to any valid directory name.

$SECRETS_PINENTRY - allows user to specify a setting for gpg ’s –pinentry option. See gpg docs for details about gpg’s –pinentry option.

The .gitsecret folder (can be overridden with SECRETS_DIR)

This folder contains information about the files encrypted by git-secret, and about which public/private key sets can access the encrypted data.

You can change the name of this directory using the SECRETS_DIR environment variable.

Use the various ‘git secret’ commands to manipulate the files in .gitsecret , you should not change the data in these files directly.

Exactly which files exist in the .gitsecret folder and what their contents are vary slightly across different versions of gpg. Thus it is best to use git-secret with the same version of gpg being used by all users. This can be forced using SECRETS_GPG_COMMAND environment variable.

Specifically, there is an issue between gpg version 2.1.20 and later versions which can cause problems reading and writing keyring files between systems (this shows up in errors like ‘gpg: skipped packet of type 12 in keybox’).

The git-secret internal data is separated into two directories:

.gitsecret/paths

This directory currently contains only the file mapping.cfg , which lists all the files your storing encrypted. In other words, the path mappings: what files are tracked to be hidden and revealed.

All the other internal data is stored in the directory:

.gitsecret/keys

This directory contains data used by git-secret and PGP to allow and maintain the correct encryption and access rights for the permitted parties.

Generally speaking, all the files in this directory except random_seed should be checked into your repo. By default, git secret init will add the file .gitsecret/keys/random_seed to your .gitignore file.

Again, you can change the name of this directory using the SECRETS_DIR environment variable.

Command Reference