Protecting your secrets, keys and certificates

Yaybu natively supports the use of GPG as a way to protect both secret variables in your configuration files and the use of encrypted assets when using the Provisioner part.

Installing GPG

On an Ubuntu machine GPG can be installed with:

sudo apt-get install gnupg

On OSX you can install a pre-built binary produced by the GPGTools team, or you can install it using brew:

brew install gnupg

Creating a GPG key

If you want to encrypt your secrets for multiple recipients you will need a GPG key. We tend to follow the advice of Debian when creating new keys and as such:

  • You should go for a 4096 bit key
  • You should avoid SHA1 as your preferred hash

You can generate a signing and encryption key has follows:

paul@jolt:~$ gpg --gen-key
gpg (GnuPG) 1.4.10; Copyright (C) 2008 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

gpg: directory `/home/paul/.gnupg' created
gpg: new configuration file `/home/paul/.gnupg/gpg.conf' created
gpg: WARNING: options in `/home/paul/.gnupg/gpg.conf' are not yet active during this run
gpg: keyring `/home/paul/.gnupg/secring.gpg' created
gpg: keyring `/home/paul/.gnupg/pubring.gpg' created
Please select what kind of key you want:
   (1) RSA and RSA (default)
   (2) DSA and Elgamal
   (3) DSA (sign only)
   (4) RSA (sign only)
Your selection? 1
RSA keys may be between 1024 and 4096 bits long.
What keysize do you want? (2048) 4096
Requested keysize is 4096 bits
Please specify how long the key should be valid.
         0 = key does not expire
      <n>  = key expires in n days
      <n>w = key expires in n weeks
      <n>m = key expires in n months
      <n>y = key expires in n years
Key is valid for? (0) 0
Key does not expire at all
Is this correct? (y/N) y

You need a user ID to identify your key; the software constructs the user ID
from the Real Name, Comment and E-mail Address in this form:
    "Heinrich Heine (Der Dichter) <heinrichh@duesseldorf.de>"

Real name: Paul Ubbot
E-mail address: pubbot@example.com
Comment:
You selected this USER-ID:
    "Paul Ubbot <pubbot@example.com>"

Change (N)ame, (C)omment, (E)-mail or (O)kay/(Q)uit? O
You need a Passphrase to protect your secret key.

We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, use the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.

Not enough random bytes available.  Please do some other work to give
the OS a chance to collect more entropy!  (Need 284 more bytes)
+++++
...............................+++++
We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, use the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
......+++++
.......+++++
gpg: /home/paul/.gnupg/trustdb.gpg: trustdb created
gpg: key D770E8A9 marked as ultimately trusted
public and secret key created and signed.

gpg: checking the trustdb
gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model
gpg: depth: 0  valid:   1  signed:   0  trust: 0-, 0q, 0n, 0m, 0f, 1u
pub   4096R/D770E8A9 2013-08-28
      Key fingerprint = 746B 2477 FB6F CCC6 46C2  D5D2 288C EF6D D770 E8A9
uid                  Paul Ubbot <pubbot@example.com>
sub   4096R/49BEE9E3 2013-08-28

You now have a GPG key.

Ideally you should sign the keys of the people you are working with to build a web of trust, however there is no requirement to do so. There are excellent resources online for holding a key signing event.

In order to encrypt for you collaborators will need a copy of the public portion of your key. You can publish your key like so:

gpg --keyserver pgp.mit.edu --send-key D770E8A9

Anyone can retrieve your public key like so:

gpg --keyserver pgp.mit.edu --recv-keys D770E8A9

Encrypting your configuration

You might have a secrets.yay that looks like this:

secrets:
    aws: somepassword
    rackspace: abetterpassw0rd

You can encrypt it for your new key like this:

gpg -e -r D770E8A9 secrets.yay

You can use e-mail addresses as well:

gpg -e -r pubbot@example.com secrets.yay

In both cases a secrets.yay.gpg will be generated, which you can then reference from your Yaybufile:

include "secrets.yay.gpg"

new Compute as myserver:
    driver:
        id: EC2
        key: myawskey
        secret: {{ secrets.aws }}
    <snip>

Encrypting your provisioner assets

The Provisioner part is GPG aware. If you were copying a file to a server that was a secret you could encrypt it as above and then refer to it from File parts:

new Provisioner as p:
    resources:
      - File:
          name: /etc/defaults/foobar
          static: foobar.gpg

In this situation Yaybu would notify you when it changed the file, but it wouldn’t show a diff as it knows the file is encrypted and so secret.

Integration with VIM

We are big fans of the vim-gnupg plugin which allows you to:

vi secrets.yay.gpg

It will transparently decrypt the file, allow you to edit the text contents, then when you save it will re-encrypt it. It will preserve the same recipients, which is very useful if you are working with a team.

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