Keys and Networks

When using UMA infrastructure, you often have to open the truffle console or run a script using truffle exec. When using truffle in the context of this repository, it’s important to understand what types of keys you can use and what to specify for the --network argument.

Public Networks

Public networks include the Ethereum mainnet and any public testnets, like Rinkeby, Kovan, or Ropsten. If you are using these networks, you’ll generally need to know:

  1. Which public network you intend to use.

  2. What private key you want to use and how your private keys are stored.

The --network parameter that’s passed to all truffle commands depends on both of these factors. Here’s an example:

$(npm bin)/truffle console --network rinkeby_mnemonic

That command will tell truffle that the user wants to use the Rinkeby testnet and their private key is a mnemonic, or seed phrase. Generally, the network argument is structured as --network [NETWORK_NAME]_[KEY_TYPE]. The only exception is if you don’t provide a key type, it will fall back to a Google Cloud keystore that the UMA team uses internally. That type of key will not be documented here.

Mnemonic, or seed phrase (less secure)

Mnemonics are much less secure than using a hardware wallet, but they are also much faster when sending multiple transactions since they don’t require as much user input. If you’d like to use a mnemonic, you’ll need to start by putting the mnemonic in your shell environment. Do this by running the following command:


With a real mnemonic, this would look like:

export MNEMONIC="candy maple cake sugar pudding cream honey rich smooth crumble sweet treat"

Once you’ve done that you’re ready to run a truffle command. When using a mnemonic, your network argument should look be --network [NETWORK_NAME]_mnemonic. So, for example, using a mnemonic on kovan would look like:

$(npm bin)/truffle console --network kovan_mnemonic

Hardware wallets (more secure)

Hardware wallets are the more secure way to interact with the system on public networks. We currently only support Ledger hardware wallets, but we plan on supporting more in the future.

To set up a Ledger hardware wallet for use with our system:

  1. Connect the device to your machine.

  2. Use your passcode to unlock it.

  3. Ensure the Ethereum app is installed on your device. Install it if not.

  4. Select the Ethereum app on the device.

  5. Go to the Ethereum app settings on the device and change the "Contract data" setting to yes if it isn’t already.

Now that you’re set up, you should be able to run truffle commands with the network argument --network [NETWORK_NAME]_ledger.

For example, you could connect your ledger wallet to the truffle console and begin running commands against mainnet with the following command:

$(npm bin)/truffle console --network mainnet_ledger

Note: outgoing transactions will require manual approval on the ledger device. If you fail to approve, the command will hang.

© UMA Project 2018-2019