Security warning for Transacting on Shared nodes
When using a shared node like the free trial version of the Open Application Network Blockdaemon node, you should never use the unlockAccount function in order to make a transaction (either manually on a terminal or through a smart contract). Doing so exposes your private keys and could result in loss of funds.
Best practices for transacting on a shared node
If you want to transact on shared nodes the best practice is to NOT unlock account because it will make your account's personal functions(e.g. send transaction) available to anyone for a period of time that your account is unlocked on that node.
KEEP YOUR PRIVATE KEY SAFE
Make sure to secure your private key, don't push it to any repositories or any cloud services, make sure it's secure and available only to you.
Consider your private key a key to a publicly available safe.
If you already have a keystore generated by the wallet and you want to extract your private key from it to transact you can install the aion node, import your keystore into the keystore folder and run:
./aion.sh export <account address>
(node doesn't have to be synced or connected to any peers).