How is it possible that Web3j is send Transaction over Infura.io?

Question

Infura can't unlock Accounts over JSON RPC/web3.js infura FAQ. How is it possible that Web3j can send Transaction over Infura.io?

Web3js uses also JSON RPC to communicate with the Blockchain. So they have to be an option to do this also with JSON RPC.

For Information: I use web3j with android and are connected to rinkbey testnet with Ianfura. I use the Credentials method to load unlock my account.

Can someone explain this?

Answer 1

You need to sign the transaction locally and push the signed transaction to infura with eth_sendrawtransaction

You can sign a transaction with web3.eth.accounts.signTransaction(tx, privateKey [, callback]);