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Keyfob

keyfob is a two-factor authentication agent suitable for AWS and Github. Works pretty much the same as Google Authenticator or Authy, but uses your laptop's keychain.

Installation

If you use homebrew:

brew tap StevenACoffman/keyfob
brew install keyfob

Any subsequent releases should get picked up automatically with brew upgrade

If don't use homewbrew, and you're on a mac, you can just do this:

wget -O - https://raw.githubusercontent.com/StevenACoffman/keyfob/master/install.sh | bash

This will download the github 0.3.0 binary release for mac, and move any of your MFA secrets from 2fa over to your keychain.

Usage

keyfob add [name] [key]
keyfob otp [name]
keyfob list
keyfob qr [name]
keyfob vault [name] [profile]
keyfob help

  • keyfob add name adds a new key to the keyfob keychain with the given name. It prints a prompt to standard error and reads a two-factor key from standard input. Two-factor keys are short case-insensitive strings of letters A-Z and digits 2-7.

    The new key generates time-based (TOTP) authentication codes.

  • keyfob otp [name] prints a One Time Password (aka two-factor authentication) code from the key with the given name. If --clip is specified, keyfob also copies to the code to the system clipboard.

  • keyfob list prints the names of all the added keys, if any.

  • keyfob qr [name] prints a QR Code for the key with the given name. This can be useful for backing up QR Codes to Google Authenticator or Authy or whatever.

  • keyfob vault [name] [profile] acts as a will act as an AWS credential helper using AWS Vault and a One Time Password.

The Time-based One Time Password (TOTP) authentication codes are derived from a hash of the key and the current time, so it is important that the system clock have at least one-minute accuracy.

The keychain is stored unencrypted in the text file $HOME/.keyfob.

Example

During GitHub 2FA setup, at the “Scan this barcode with your app” step, click the “enter this text code instead” link. A window pops up showing “your two-factor secret,” a short string of letters and digits.

Add it to keyfob under the name github and append the secret:

$ keyfob add github nzxxiidbebvwk6jb

Then whenever GitHub prompts for a 2FA code, run keyfob to obtain one:

$ keyfob otp github
268346

Derivation (Credit where Credit is due)

This is just a little toy cobbled together from 2fa, cobra, and go-keyring and using goreleaser. The directions I had below this were confusing, so I stole some of the directions from this article on how to do a similar thing with a yubikey.

Really, does this make sense?

At least to me, it does. My laptop features encrypted storage, a stronger authentication mechanism, and I take good care of its physical integrity.

My phone also runs arbitrary apps, is constantly connected to the Internet, gets forgotten on tables.

Thanks to the convenience of a command line utility, I'm more likely to enable MFA in more places.

Clearly a win for security.

Dependencies

OS X

The OS X implementation depends on the /usr/bin/security binary for interfacing with the OS X keychain. It should be available by default.

Linux

The Linux implementation depends on the [Secret Service][SecretService] dbus interface, which is provided by GNOME Keyring.

It's expected that the default collection login exists in the keyring, because it's the default in most distros. If it doesn't exist, you can create it through the keyring frontend program Seahorse:

  • Open seahorse
  • Go to File > New > Password Keyring
  • Click Continue
  • When asked for a name, use: login

Usage with aws-vault

This assumes you have installed keyfob and aws-vault but need to set up your secrets. See aws-vault for instructions on setting that up.

Note: Your own organization might have a different preferred source_profile name from source below, and your AWS account number is probably not 111111111111.

  1. Skip to 2 if you already added your AWS access key and secret access key to aws vault. Otherwise do this:
$ brew cask install aws-vault
$ brew install go zbar awscli
$ aws-vault add source --keychain login

  1. Go to the AWS Web console to make a new MFA token.

  2. After login, go to IAM > Users and click in your user name. Then you need to click on the “Security credentials” tab.

  1. To assign an MFA device, just click Manage. If you have an existing one, you must remove it. In the next screen, select “Virtual MFA device”.

  1. Here you can choose to show the QR code or to show the text of the MFA secret key. For our purposes, we want the secret key only.

  1. Add your MFA secret (from above) to keyfob:
keyfob add aws-source <YOUR_BASE_32_KEY>
  1. Then run keyfob otp aws-source a few times, to get two different, but consecutive 6-digit codes and complete the set up.

  1. Add to your .aws/config file something like this:
[default]
credential_process = keyfob vault aws-source engineer
region = us-east-1
output = json
 
[profile source]
region = us-east-1
mfa_serial = arn:aws:iam::111111111111:mfa/scoffman
 
[profile engineer]
mfa_serial = arn:aws:iam::111111111111:mfa/scoffman
region = us-east-1
role_arn = arn:aws:iam::111111111111:role/put-power-role-here
source_profile = source
  1. Run aws-vault add source --keychain login and provide your AWS secret access key and AWS access key when prompted.

Here default profile depends on engineer profile which depends on source profile.

  1. The default profile specifies a credential_process, which will tell keyfob to use the engineer profile when invoking aws-vault
  2. The engineer profile specifies a source_profile which uses the source profile for credentials in aws-vault.
  3. The source profile has credentials stored by aws-vault in the keychain.
💡 NOTE: Make sure you've edited and replaced the AWS account, userid, and power-role above.

If your AWS user doesn't need to assume a privileged role, then omit the engineer profile and use keyfob vault aws-source source as the credential_process.

You also don't have to make the keyfob profile be the default, but some AWS SDKs (looking at you Java) may struggle otherwise.

You also may want to export something like these environment variables in your .bash_profile or .bashrc (or whatever zsh uses):

export AWS_MY_USERNAME='scoffman'
export AWS_SDK_LOAD_CONFIG=true
export AWS_REGION="us-east-1"
export AWS_DEFAULT_REGION="us-east-1"
export AWS_DEFAULT_OUTPUT="json"
export AWS_VAULT_KEYCHAIN_NAME='login'
export AWS_MFA_NAME='aws-source'
# 3600s is max for chaining roles
export AWS_ASSUME_ROLE_TTL='3600s'
export AWS_SESSION_TTL='12h'
export AWS_FEDERATION_TOKEN_TTL='12h'