From BIP47 on mediawiki:
https://github.com/bitcoin/bips/blob/master/bip-0047.mediawikistep 3 of the notification tx:
3. Alice serializes her payment code in binary form.
According the Binary Serialization on the same page,
the Payment Code is essentially
Alice's pubkey (A = a * G) and
Alice's Chain Code(c)
in the next step:
4. Alice renders her payment code (P) unreadable to anyone except Bob:
i. Replace the x value with x':
The problem is x is the x coordinate of the secret point S = a * B = (x, y)
where a is Alice's privatekey and B is Bob's publickey point (B = b * G)
Question: even if I replace x by x', it won't change the value of the Payment Code
since x is not involved in this value !
What I'm missing ?