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Setting up the keyring

Synopsis

This document describes how to configure and use the keyring and its various backends for an application.

The keyring holds the private/public keypairs 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 sub-system 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 passwords manager:

GNU/Linux distributions that use GNOME as default desktop environment typically come with Seahorse. Users of KDE based distributions are commonly provided with KDE Wallet Manager. Whilst the former is in fact a libsecret convenient frontend, the latter is a kwallet client.

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:

# 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 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 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:

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 ships KDE as default desktop environment. Please refer to KWallet Handbook for more information.

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 the 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​

danger

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.

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.

$ 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.