Use of nonce in Gas Station Network

[abcoathup]

The nonce is used in the Gas Station Network to mitigate against the following attacks described in the EIP:

• Attack: Relay attempts to censor a transaction by signing it, returning it to the sender, but never putting it on the blockchain.

• Attack: Relay attempts to censor a transaction by signing it, but publishing a different transaction with the same nonce.

• Attack: Relay attempts to censor a transaction by signing it, but using a nonce higher than it’s current nonce.

• Attack: Attacker attempts to replay a relayed transaction.

• Attack: User does not execute the raw transaction received from the Relayer, therefore blocking the execution of all further transactions signed by this relayer