Moac Travis-CI Code Climate Gitter

Forking from ruby-eth, I’ll really have to thank him.

A simple library to build and sign Ethereum transactions. Allows separation of key and node management. Sign transactions and handle keys anywhere you can run ruby, broadcast transactions through any node.


Add this line to your application’s Gemfile:

ruby gem 'moac'

And then execute:

$ bundle

Or install it yourself as:

$ gem install moac_eth



Create a new public/private key and get its address:

ruby key = key.private_hex key.public_hex key.address # EIP55 checksummed address

Import an existing key:

ruby old_key = priv: private_key

Or decrypt an encrypted key:

ruby decrypted_key = Moac::Key.decrypt'./some/path.json'), 'p455w0rD'

You can also encrypt your keys for use with other ethereum libraries:

ruby encrypted_key_info = Moac::Key.encrypt key, 'p455w0rD'


Build a transaction from scratch:

ruby tx ={ data: hex_data, gas_limit: 21_000, gas_price: 3_141_592, nonce: 1, to: key2.address, value: 1_000_000_000_000, })

Or decode an encoded raw transaction:

ruby tx = Moac::Tx.decode hex

Then sign the transaction:

ruby tx.sign key

Get the raw transaction with tx.hex, and broadcast it through any Ethereum node. Or, just get the TXID with tx.hash.


Validate an EIP55 checksummed address:

ruby Moac::Utils.valid_address? address

Or add a checksum to an existing address:

ruby Moac::Utils.format_address "0x4bc787699093f11316e819b5692be04a712c4e69" # => "0x4bc787699093f11316e819B5692be04A712C4E69"


In order to prevent replay attacks, you must specify which Ethereum chain your transactions are created for. See EIP 155 for more detail.

ruby Moac.configure do |config| config.chain_id = 1 # nil by default, meaning valid on any chain end


Bug reports and pull requests are welcome on GitHub at Tests are encouraged.


First install the Ethereum common tests:

shell git submodule update --init

Then run the associated tests:

shell rspec


The gem is available as open source under the terms of the MIT License.


  • Better test suite.
  • Expose API for HD keys.
  • Support signing with libsecp256k1.