x1 is private/personal/privy/[secret/confidential/confined] to x2; x1 is not-public/hidden.
Also: x1 is secret (one sense); x2 is in the know/in touch with/privy to x1 (= selsivni for reordered places); exclusion can be expressed by na'e(bo) in x2: excluded/in the dark (= nalselsivni). See also gubni, mipri.