Paymasters and transaction submission

Hiding the user as on-chain sender and reimbursing fees from the pool

Private transfers aim to hide who is transacting. On Starknet, the transaction sender is visible—so users often submit through a paymaster service.

Flow

1. User builds proof + server-side actions and sends them to the paymaster.
2. Paymaster broadcasts the transaction from its account and pays fee in ETH/strk.
3. User includes a Withdraw (or similar) in the same transaction to send fee reimbursement from the pool to the paymaster’s public address.

On-chain, observers see the paymaster as sender; they do not see the user’s Starknet address as the transaction origin.

Trust model

• Paymaster learns IP and whatever the client sends; it should not learn more than necessary if the payload is minimal.
• Choose paymasters with clear privacy and retention policies.

Related: Security, Transaction flow.