Transaction Relay enables transaction fees of Ethereum contracts and transactions to be paid by any Currency
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Latest commit 7fd8786 Oct 23, 2016 @iurimatias committed on GitHub Merge pull request #2 from iurimatias/embark2

Transaction Relay

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Transaction Relay enables transaction fees of Ethereum contracts and transactions to be paid by any Currency (EIP20 compatible).

There are 2 roles in Transaction Relay:

  • Requester: The user who wants to issue a transaction and pay in some token. The request is signed and broadcasted over Whisper.
  • Relayer: The user who picks up the transaction and is willing to deploy it in exchange for the tokens proposed.

The contract will verify the transaction was deployed and compensate the Relayer.

Transaction Relay is currently Alpha.

Possible Applications

  • Contracts and transactions can be paid in different currencies that a user might find more convenient.
  • 'pay-to-play' used to be the only model possible in Ethereum, in this model the issuer of the transaction needs to be able to own ether to pay for the interaction, TransactionRelay enables 3rd parties to take in the fee cost by issuing tokens to registered addresses. This could be useful for applicatiosn where the developer doesn't expect the user to own ether easily to pay for the transactions to interact with a specific dapp or contract. It could also be used for controlled interactions e.g giving a use 10 free roulette spins, or accepting x free posts submissions per day for a registered user in a forum.
  • Previously a blocker for some altcoins to migrate to ethereum as tokens was that their transactions would need to be paid in Ether. TransactionRelay enables their transactions to be paid 'natively'.


Since the relayer is the one doing the transaction, then the contract will see msg.sender as the address of the relayer not the issuer. It's possible to put a signature in the transaction itself but a contract would need to know how to deal with this. Another alternative is to deploy a proxy contract A that has permissions to interact with another contract B. contract A can verify the signature and then interact with contract B.

To do next

  • Improve the signature process to prevent some potential attack vectors
  • Implement a market mechanism of the tokens<->ether rate