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A backend for the `keyring` module which uses a hardware token to require user presence for any secret access, by encrypting your vault and passwords as Fernet tokens.

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TokenRing

TokenRing is a back-end for the Python keyring module, which uses a hard token to encrypt your collection of passwords as a large Fernet token, composed of individual password entries, each of which is separately encrypted as a smaller Fernet token of its own.

Background and Threat Model

The keyring module is a great starting point for managing confidential materials in your Python applications. Anything that needs to connect to a network-backed service for an account requires some kind of saved password or API token for nearly every operation. By using the keyring API, you give the user control over how that information is accessed, via configuration and plugins.

However, using its default backend on every platform, Keyring provides silent access to your credentials. Only macOS even provides a mechanism that could require user interaction to access a credential; Windows provides literally nothing and desktop Linux provides only the ability to temporarily lock all secrets behind your login password.

For a lot of applications, this is fine; “arbitrary code execution on your computer” is a pretty high bar for an attacker to achieve, and there's a lot of nasty stuff they can get up to if they get it; it would be annoying to have to log in once every 30 seconds so that background tasks could check your email or on every single git fetch.

But some operations are dangerous and infrequent enough that your computer should really not be able to do them without you noticing. Just for a couple of examples: uploading widely-used packages to PyPI that can execute code on millions of computers, or issuing bank transfers to your payment provider.

This is where tokenring comes in.

Requirements

You need to have an NFC authenticator with the hmac-secret extension. In practice, in my limited experience, this means a YubiCo authenticator of some recent vintage.

Usage

Step 0: make sure the software that you're using uses keyring to fetch its secrets

Many things which handle sensitive information do, but you might need to submit a patch first.

Step 1: install tokenring into the environment where you're accessing extra-sensitive secrets

You probably don't want tokenring globally installed; or indeed installed in most of your Python environments, since it is a high-priority backend that will take over for all Keyring API calls by default, and therefore require your hard-token to access every time.

For example, let's say you upload all your packages with twine. First, install twine itself with pipx so it gets its own dedicated virtual environment. Then, pipx inject twine --include-apps tokenring; since this always injects keyring as well, twine will always use tokenring as a backend.

Step 2: run the agent

This is currently mandatory on Windows due to this issue unless you are running your application as an administrator. On other platforms, it'll fall back to local access within the requesting process, but you'll have to tap your authenticator one extra time per process in that case, to unlock the vault.

pipx install tokenring, and run tokenring agent path/to/your/tokenring.vault.

Step 3: call keyring.set_password and keyring.get_password in whatever application you'd like to use

If the keyring command on your shell's PATH is in an environment with tokenring installed, you can just use keyring set and keyring get to test this, but as a convenience, to make sure you're inspecting tokenring directly, you can use the tokenring set and tokenring get commands, which behave similarly but will never use any other keyring backend.

To use Twine with a secret stored in tokenring, for example, the full workflow would be:

  1. open a terminal and run tokenring agent my.vault
  2. create a token at https://pypi.org/manage/account/token/
  3. open a terminal and run tokenring set https://upload.pypi.org/legacy/ __token__, then paste your token when prompted
  4. in whatever project you'd like to upload, TWINE_USERNAME=__token__ twine upload dist/*

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A backend for the `keyring` module which uses a hardware token to require user presence for any secret access, by encrypting your vault and passwords as Fernet tokens.

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