Example:
I have(I know private keys) 2 unspent "addresses" a1=5 XMR and a2=5 XMR, I want pay for goods 2 XMR (address g1.) and send the rest to a3. To confuse observer I'll use both input addresses.
Transaction
input ( a1=5 XMR, a2=5XMR ) output( g1=2 XMR, a3= 8 XMR )
I'll ring-sign with a1 private key, Is this correct ?
Almost. You will will sign with both a1 and a2 private keys, allowing you to spend both outputs.
If you want to ring sign (it is optional) you can also include in the ring sig additional
public keys from other outputs that you don't control (you just pull them from the blockchain). The observer can't tell which of the outputs was the actual source (where you hold the private key) but can verify that there is a valid private key being used for each input.
Hope that helps!
lol, I'm still confused:-)
So I'll send 2 transaction, is this possible ?
input ( a1=5 XMR, a2=5XMR ) output( g1=2 XMR, a3= 8 XMR ) -> ring-sing with a1
input ( a1=5 XMR, a2=5XMR ) output( g2=2 XMR, a4= 8 XMR ) -> ring-sing with a2