keyfork/README.md

# keyfork #

An opinionated and modular toolchain for generating and managing a wide range
of cryptographic keys offline and on smartcards from a shared bip39 mnemonic
phrase.

This toolchain uses a bip32 seed loaded into an agent to generate deterministic
and unique keypairs. This ensures only the agent has control over the mnemonic
itself, and other components can simply request deterministic data.

This repository must not be managed by `cargo-hakari`, to ensure each plumbing
binary can be built with as few dependencies and SLOC to review as possible.

## Dependency Policy

Dependencies must not be added to core utilities such as seed generation and
path derivation without a _really_ good reason we can't implement it ourselves,
such as cryptography libraries. For instance, `keyfork-derive-util` _only_
utilizes cryptography libraries, `serde`, and `thiserror`, with the latter two
being audited dependencies. Utilities such as forklets (applications that
use derived data, such as an OpenPGP keychain generator) and the kitchen-sink
`keyfork` utility may pull in additional dependencies _as needed_, but should
strive to use the standard library as much as possible. To avoid code reuse,
additional crates (such as the `smex` crate) may be used to share functionality
across several crates.

## Keyfork Top-Level Binary

The `keyfork` binary is the most user-friendly interface for interacting with
the Keyfork toolchain. It offers commands that should not take any scriptable
input and should not produce any script-readable output. Such operations that
require script compatibility should be made into their own utilities, with the
higher level interface of interacting with them left solely to `keyfork`.

For instance, the program to generate system entropy is `keyfork-entropy`. It
accepts an arbitrary length and spits out a hex-encoded chunk of data. The
program to convert that entropy into a seed is `keyfork-mnemonic-from-seed`. It
takes entropy from input and converts it into a seed. The combination of the
two, generating entropy and converting it to a mnemonic, is managed through
Keyfork: `keyfork mnemonic generate`, which can also be used to offer more
options down the line, such as generating a mnemonic from tarot or playing
cards, or dice.

---

Note: The following document is all proposed, and not yet implemented.

## Features

  * Modular
    * Standalone binaries can derive/manage keys/config from bip32 root
    * Modules handle use cases like ssh, pgp, webauthn, crypto-assets, etc
    * Module contract is dead simple and can be written in any language
  * Recoverable
    * Config file and 24 word mnemonic phrase to recover -all- keys
  * Unpredictable
    * Generate a BIP39 phrase from OS entropy
    * Take BIP39 passphrase from user supplied entropy
    * Read up on [https://milksad.info](milksad) to understand why this matters!
  * Offline
    * Will exit if network access is detected to force you to keep keys offline
    * Helps limit the risk of supply chain attacks
    * Intended for use with QubesOS Vault VM, AirgapOS, etc
    * Private keys are installed to HSMs/TEEs for use by online machines

## Install

These steps will allow you to prove that at least two Distrust engineers
signed off on the produced binaries, signaling that they reproduced them from
source code and got identical results, in addition to our usual two-party code
review processes.

This minimizes a single point of trust (and failure) in our binary release
process.

See the [Reproducible Builds](https://reproducible-builds.org/) project for
more information on these practices.

We use git for all development, releases, and signing. Unfortunately git has no
native method for large file storage or multi-signature workflows so some git
add-ons are required.

To follow these steps please install [git-lfs][gl] and [git-sig][gs].

[gs]: https://git.distrust.co/public/git-sig
[gl]: https://git-lfs.com

1. Clone repo

    ```sh
    git clone https://git.distrust.co/public/keyfork
    cd keyfork
    ```

2. Review binary signatures

    ```sh
    git sig verify
    ```

    Note: See Trust section below for expected keys/signers

3. Install binary

    ```
    make install
    ```

## Basic Usage

### Personal Setup

On an airgapped system, run the following command to generate a BIP-0039
mnemonic encoding a generated seed:

```sh
keyfork mnemonic generate
```

Once generated, the mnemonic should be written down and stored in a secure
location such as a safe.

<!--
The default format is to use system entropy, but playing cards, tarot cards, or
dice can be used to generate physical entropy
-->

The Keyfork server can be started by running the following command:

```sh
keyfork recover mnemonic
```

### Group Setup

This guide assumes you are sharding to an `N`-of-`M` system with `I` smart
cards per shardholder. The variables will be used in the following commands as
`$N`, `$M`, and `$I`. The smart cards will be factory reset during the process.

On an airgapped system, run the following command to generate a file containing
encrypted shards of a generated seed:

```sh
keyfork wizard generate-shard-secret --threshold $N --max $M --keys-per-shard $I > shards.pgp
```

Once generated, the shards file can be safely stored in any location, as the
only information that can be obtained from the shard file is the `$N` value.

If all shardholders are physically present, the Keyfork server can be started
by running the following command:

```sh
keyfork recover shard
```

Otherwise, the Keyfork server can be started by transporting the shards to the
machine using the following command:

```sh
keyfork recover remote-shard
```

Each shard can be transported by running the following command:

```sh
keyfork shard transport shard.pgp
```

### Deriving Keys

Keys can be derived from Keyfork using the `keyfork derive` command, such as
the following command for an OpenPGP certificate with one of each subkey:

```sh
keyfork derive openpgp "Ryan Heywood (RyanSquared) <ryan@distrust.co>"
```

## Usage

Detailed usage instructions can be found in the `keyfork-user-guide` mdBook,
which can be opened in-browser by running
`mdbook serve --open keyfork-user-guide`.

<!--
```
keyfork generate [-c,--config=<file>]
    Generate new mnemonic optionally public keys defined by config
keyfork recover [-c,--config=<file>] [-a,--agent]
    Recover keychain and optionally config defined pubkeys from mnemonic
    Optionally run a daemon to supply keys to subcommands
keyfork version
	Show version information.
keyfork help
    Show this text.
keyfork [command]
    Commands receive bip32 root as stdin
    Commands return output and config data as json over stdout back to keyfork
keyfork [command] help
    Show help for a particular sub-command
```

## Examples

#### Generate a new mnemonic to write to paper

```
$ keyfork generate

> milk sad wage cup reward umbrella raven visa give list decorate bulb gold raise twenty fly manual stand float super gentle climb fold park
```

#### Recover a mnemonic with a passphrase and spawn agent

```
$ keyfork recover --agent

> mnemonic: ********
> passphrase: ********

```

#### Derive deterministic PGP keychain from agent key in default "sq" path

Requires ```keyfork-pgp``` binary in $PATH

```
$ keyfork pgp --format=sq
$ sq decrypt secret.pgp
```

#### Install deterministic PGP subkeys from agent key to a smartcard

Requires ```keyfork-pgp``` binary in $PATH

```
$ keyfork pgp install --device=nitrokey
$ gpg --card-status
```

#### Install first deterministic PIV key from agent key to smartcard on slot 1

Requires ```keyfork-piv``` binary in $PATH

```
$ keyfork piv install --device=yubikey --key=1 --slot=1

> Management Key: ****
> User Pin: ****
> Admin Pin: ****

$ ssh-keygen -D "$OPENSC_LIBS/opensc-pkcs11.so" -e
```

#### Derive first deterministic BIP44 address for Bitcoin Account 1

Requires ```keyfork-bip44``` binary in $PATH

```
$ keyfork bip44 --path=bitcoin

> m/44'/0'/0'/0/0: 12DefCMhYVv4sBQikyXKMciAoX2wgzhWqb
```
-->