cardano-kit

At toolkit for Crystal to ease developing for the Cardano blockchain.

This shard consists of a series of individual modules that can be combined or used separately. The main goal is to provide a series of abstractions for complex implementations, thereby lowering the barriers to entry for development on Cardano. It's very much a work in progress, but the contained modules are ready for use in production.

Installation

1. Add the dependency to your shard.yml:

dependencies:
  cardano_kit:
    github: wout/cardano-kit

2. Run shards install

Usage

require "cardano_kit"

Address

Parse an address from bech32 to its prefix and words:

address = CardanoKit::Address.from_bech32("addr1qxdvcswn0exwc2vjfr6u6f6qndf...")
puts address.prefix
# => "addr"
puts address.words
# => Bytes[0, 4, 223, 149, 66, 179, 36, 18, 22, 136, 65, 58, 246, 181, 214, ...]

Or parse it from hexbytes using a string or bytes object:

CardanoKit::Address.from_bytes("addr", Bytes[0, 4, 223, 149, 66, 179, 36, ...])
# or
CardanoKit::Address.from_hexstring("addr", "0004df9542b324121688413af6b5d6c...")

Convert an address to bech32 format:

puts address.to_bech32
# => "addr1qxdvcswn0exwc2vjfr6u6f6qndfhmk94xjrt5tztpelyk4yg83zn9d4vrrtzs98lc..."

Find the stake address for a given address:

puts address.stake_address
# => "stake1uxyrc3fjk6kp343gznlu06w2qddk0f5d5r4znrxzg52zxlclk0hlq"

If a short address is provided without the stake address part, this method will raise a CardanoKit::NoStakeAddressException. The stake_address? variant of this method will return nil in that case, which may be preferable in some scenarios.

Finally, an address object can be initialized directly with its prefix and words arguments:

CardanoKit::Address.new("addr", Bytes[0, 4, 223, 149, 66, 179, 36, 18, 22, ...])

However, initializing it with an unknown prefix will raise a CardanoKit::UnknownPrefixExcepiton. A safer, but more verbose way to initialize an address is to use the underlying enums:

CardanoKit::Address.new(
  CardanoKit::AddrPrefix::Mainnet,
  Bytes[0, 4, 223, 149, 66, 179, 36, 18, 22, 136, 65, 58, 246, 181, 214, ...]
)

Making a typo there will result in a compile-time error, thus avoiding a dreaded runtime error. Available values are:

CardanoKit::AddrPrefix::Testnet # => "addr_test"
CardanoKit::AddrPrefix::Mainnet # => "addr"
CardanoKit::AddrPrefix::StakeTestnet # => "stake_test"
CardanoKit::AddrPrefix::StakeMainnet # => "stake"

CIP08

An implementation of CIP08 for wallet signature verification on Cardano.

Most common use cases:

1. Proving ownership of a set address.
2. Proving ownership of addresses used in a transaction.
3. Proving ownership of an identity or other off-chain data with a public key attached to it.

cip08 = CardanoKit::CIP08.new(key, signature)

# validate the signature
if cip08.signature_valid?
  # get the message
  puts cip08.message
  # => "Hello Crystal!"

  # define the address prefix based on the used network (1 is mainnet, 0 for testnets)
  prefix = CardanoKit::AddrPrefix.from_value(1)

  # get the address object
  puts cip08.address(prefix).to_s
  # => "addr1qqe63xlwltvt0dehyzqdn82eugy79egwzr35pwuu3wrzeqglaeslj4r7yyt83kt..."
else
  puts "Invalid signature!"
end

Alternatively, the CIP08 object can be initialized with the signed data object provided by the client. This will relieve you from having to parse the user data and it adds an extra layer of type safety:

json_from_client = %({"key":"...","signature":"..."})
signed_data = CardanoKit::CIP08::SignedData.from_json(json_from_client)
cip08 = CardanoKit::CIP08.new(signed_data)

Note: In its current state, this library won't look in the headers of the signature, so the COSE key should be provided separately.

Development

Make sure you have Guardian.cr installed. Then run:

$ guardian

This will automatically:

• run ameba for src and spec files
• run the relevant spec for any file in the src dir
• run spec a file whenever it's saved

Contributing

1. Fork it (https://github.com/wout/cardano-kit/fork)
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Contributors

• Wout - creator and maintainer