Topic: [ANN]Spectrecoin[XSPEC] TOR+OBFS4, Ring Sig, Stealth! - page 107. (Read 94882 times)

The Anatomy of a ‘Stealth Payment’
1. As the beneficiary of funds you publish a spending PubKey (which is the ‘stealth address’ generated by your wallet or by using the getnewstealthaddress RPC call in the command console. You keep the associated spend Key secret.
2. As a sender, you will combine the spending PubKey, with an ephemere (transitory or temporary) random key called Ephem Key that will generate a Stealth PubKey and also a Spectrecoin address to which to pay the agreed amount.
3. As the beneficiary you will receive the Ephem PubKey and you will combine your Spend Key to retrieve the Stealth Key to spend the funds sent to the generated Spectrecoin address.

However, there is a fundamental issue to overcome in this process as there is no automatic way to send the Ephem PubKey from sender to beneficiary.
The solution is to include the Ephem PubKey in the same transaction that send the funds to the Spectrecoin Address. In this transaction two TxOut will be generated: The payment to the Spectrecoin Address (Spendable output) and an unspendable TxOut with the Ephem key embedded in it. We call such unspendable TxOut the Stealth Metadata and the pair of TxOut a Stealth Payment.

4. Then as the beneficiary you will scan all the transactions with such Stealth Payments on the Spectrecoin network and extract the Ephem PubKey and then you will generate the Stealth Key and check if it’s address match the one in the spendable output.

As a beneficiary you want to automate scanning for incoming payments. However, you don’t want to expose the secret Spend Key as that would enable a malicious actor to steal your coins.
The solution is to introduce a Scan Key that will be used to generate and scan the Stealth PubKey. In this way the scanner will be able to report your balance by scanning the blockchain without the need of the Spend Key.
However, now the sender need two pieces of information to pay you : The Scan PubKey + the Spend PubKey and both these two are derivable from the ‘Stealth address’ you publicly share.