KERI Registrar Backer on Cardano

A KERI witness that anchors key events on Cardano blockchain.

Feaures

• Cardano Address is derived from the same Ed25519 seed (private key) used to derive the prefix of the backer
• Anchoring KELs from multiple prefixes
• Queue events during a period of time to allow several block confirmations as a safety meassure
• Optional funding address to fund the backer address

Previous and related work

• keri-roots
• original keripy PR

Installation

pip install -e .

Check installation and available commands:

$ backer --help
usage: backer [-h] command ...

options:
  -h, --help  show this help message and exit

subcommands:

  command
    info      Display registrar backer information
    query     Query KEL on ledger for a given prefix
    start     Runs KERI backer controller

Start script example

./tests/start_backer.sh

Check variables and environmental variables that you can pass to configure the backer.

Environment variables

BLOCKFROST_API_KEY

API KEY from Blockfrost. It's the only REQUIRED variable and it's needed to interact with the Cardano blockchain. Block Frost provide a free tier service with limits. Additionally, you can select Cardano mainnet or a testnet.

Be aware that the Backer Cardano address needs to be funded (transfer ADA or tADA to it). If you are using the testnet, you can fund it at Testnets faucet.

FUNDING_ADDRESS_CBORHEX

This is an OPTIONAL variable to provide the Private Key of funding address as CBOR Hex. Must be an Enterprice address (no Staking part) as PaymentSigningKeyShelley_ed25519. Note that storing private keys in an environmental variable is highly insecure !

BACKER_CONFIG_DIR

This environmental variable is used by start_backer.sh script to specify the directory to place the configuration files.

BACKER_STORE_DIR

This environmental variable is used by start_backer.sh script to specify the directory to create the database and keystore.

BACKER_URL

This environmental variable is used by start_backer.sh script to specify the URL of the backer needed to resolve OOBI and to receive queries from the agents.

BACKER_PORT

This environmental variable is used by start_backer.sh script to specify the PORT of the backer needed to resolve OOBI and to receive queries from the agents.

BACKER_SALT

This environmental variable is used by start_backer.sh script that passes it to the kli init as a SALT parameter. It's a qualified base64 salt for creating key pairs, that means that you can regenerate a backer with same AID and Cardano address.

Docker

docker build -f ./Dockerfile .  -t cardano-backer   // use --platform=linux/amd64 if needed
docker run -i -t -p 5666:5666 -e BLOCKFROST_API_KEY={API KEY} cardano-backer