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# Setting up the keyring

:::note Synopsis
This document describes how to configure and use the keyring and its various backends for an [**application**](../../learn/beginner/00-app-anatomy.md).
:::

The keyring holds the private/public key pairs used to interact with a node. For instance, a validator key needs to be set up before running the blockchain node, so that blocks can be correctly signed. The private key can be stored in different locations, called "backends," such as a file or the operating system's own key storage.

## Available backends for the keyring

Starting with the v0.38.0 release, Cosmos SDK comes with a new keyring implementation
that provides a set of commands to manage cryptographic keys in a secure fashion. The
new keyring supports multiple storage backends, some of which may not be available on
all operating systems.

### The `os` backend

The `os` backend relies on operating system-specific defaults to handle key storage
securely. Typically, an operating system's credential subsystem handles password prompts,
private keys storage, and user sessions according to the user's password policies. Here
is a list of the most popular operating systems and their respective password managers:

* macOS: [Keychain](https://support.apple.com/en-gb/guide/keychain-access/welcome/mac)
* Windows: [Credentials Management API](https://docs.microsoft.com/en-us/windows/win32/secauthn/credentials-management)
* GNU/Linux:
    * [libsecret](https://gitlab.gnome.org/GNOME/libsecret)
    * [kwallet](https://api.kde.org/frameworks/kwallet/html/index.html)
    * [keyctl](https://www.kernel.org/doc/html/latest/security/keys/core.html)

GNU/Linux distributions that use GNOME as the default desktop environment typically come with
[Seahorse](https://wiki.gnome.org/Apps/Seahorse). Users of KDE based distributions are
commonly provided with [KDE Wallet Manager](https://userbase.kde.org/KDE_Wallet_Manager).
Whilst the former is in fact a `libsecret` convenient frontend, the latter is a `kwallet`
client. `keyctl` is a secure backend that leverages the Linux kernel security key management system
to store cryptographic keys securely in memory.

`os` is the default option since operating system's default credentials managers are
designed to meet users' most common needs and provide them with a comfortable
experience without compromising on security.

The recommended backends for headless environments are `file` and `pass`.

### The `file` backend

The `file` backend more closely resembles the keybase implementation used prior to
v0.38.1. It stores the keyring encrypted within the app's configuration directory. This
keyring will request a password each time it is accessed, which may occur multiple
times in a single command resulting in repeated password prompts. If using bash scripts
to execute commands using the `file` option you may want to utilize the following format
for multiple prompts:

```shell
# assuming that KEYPASSWD is set in the environment
$ gaiacli config keyring-backend file                             # use file backend
$ (echo $KEYPASSWD; echo $KEYPASSWD) | gaiacli keys add me        # multiple prompts
$ echo $KEYPASSWD | gaiacli keys show me                          # single prompt
```

:::tip
The first time you add a key to an empty keyring, you will be prompted to type the password twice.
:::

### The `pass` backend

The `pass` backend uses the [pass](https://www.passwordstore.org/) utility to manage on-disk
encryption of keys' sensitive data and metadata. Keys are stored inside `gpg` encrypted files
within app-specific directories. `pass` is available for the most popular UNIX
operating systems as well as GNU/Linux distributions. Please refer to its manual page for
information on how to download and install it.

:::tip
**pass** uses [GnuPG](https://gnupg.org/) for encryption. `gpg` automatically invokes the `gpg-agent`
daemon upon execution, which handles the caching of GnuPG credentials. Please refer to `gpg-agent`
man page for more information on how to configure cache parameters such as credentials TTL and
passphrase expiration.
:::

The password store must be set up prior to first use:

```shell
pass init <GPG_KEY_ID>
```

Replace `<GPG_KEY_ID>` with your GPG key ID. You can use your personal GPG key or an alternative
one you may want to use specifically to encrypt the password store.

### The `kwallet` backend

The `kwallet` backend uses `KDE Wallet Manager`, which comes installed by default on the
GNU/Linux distributions that ship KDE as the default desktop environment. Please refer to
[KWallet API documentation](https://api.kde.org/frameworks/kwallet/html/index.html) for more
information.

### The `keyctl` backend

The *Kernel Key Retention Service* is a security facility that
has been added to the Linux kernel relatively recently. It allows sensitive
cryptographic data such as passwords, private key, authentication tokens, etc
to be stored securely in memory.

The `keyctl` backend is available on Linux platforms only.

### The `test` backend

The `test` backend is a password-less variation of the `file` backend. Keys are stored
unencrypted on disk.

**Provided for testing purposes only. The `test` backend is not recommended for use in production environments**.

### The `memory` backend

The `memory` backend stores keys in memory. The keys are immediately deleted after the program has exited.

**Provided for testing purposes only. The `memory` backend is not recommended for use in production environments**.

### Setting backend using an env variable 

You can set the keyring-backend using env variable: `BINNAME_KEYRING_BACKEND`. For example, if your binary name is `gaia-v5` then set: `export GAIA_V5_KEYRING_BACKEND=pass`

## Adding keys to the keyring

:::warning
Make sure you can build your own binary, and replace `simd` with the name of your binary in the snippets.
:::

Applications developed using the Cosmos SDK come with the `keys` subcommand. For the purpose of this tutorial, we're running the `simd` CLI, which is an application built using the Cosmos SDK for testing and educational purposes. For more information, see [`simapp`](https://github.com/cosmos/cosmos-sdk/tree/main/simapp).

You can use `simd keys` for help about the keys command and `simd keys [command] --help` for more information about a particular subcommand.

To create a new key in the keyring, run the `add` subcommand with a `<key_name>` argument. For the purpose of this tutorial, we will solely use the `test` backend, and call our new key `my_validator`. This key will be used in the next section.

```bash
$ simd keys add my_validator --keyring-backend test

# Put the generated address in a variable for later use.
MY_VALIDATOR_ADDRESS=$(simd keys show my_validator -a --keyring-backend test)
```

This command generates a new 24-word mnemonic phrase, persists it to the relevant backend, and outputs information about the keypair. If this keypair will be used to hold value-bearing tokens, be sure to write down the mnemonic phrase somewhere safe!

By default, the keyring generates a `secp256k1` keypair. The keyring also supports `ed25519` keys, which may be created by passing the `--algo ed25519` flag. A keyring can of course hold both types of keys simultaneously, and the Cosmos SDK's `x/auth` module supports natively these two public key algorithms.
