Next step is configuring the key material. We want to transmit signed transactions that contain the prices to be fed in the oracle. Therefore the off-chain worker needs to know the key pairs of Alice, Bob and Charlie (yes, he's also going to take part in this example). Usually the key pairs would be imported, e. g. from a file. But as for the chain nodes we use the predefined key material which is addressed by //[Name]. We derive those key pairs from the keyring we create specifying the key pair format SR25519.