Prove that the following private-key encryption scheme is not CPA-secure Consider the following private-key encryption scheme : The shared key is k $\in$ {0,1}n. To encrypt the message m $\in$ {0,1}n, choose random r $\in$ {0,1}n and output $(r, F_r(k)\oplus \overline{m})$, where $F$ is a block cipher and $\overline{m}$ is the bit-wise compliment of m. Is this scheme CPA secure?

What is the importance of bit-wise compliment in this question?

Also, it does seem that the scheme is CPA secure because one is performing a $\oplus$ of a message string and a random string (it would change for every message as we pick a random r for each m)
If you choose $m = (1, \ldots, 1)_n$ then

$$(r, F_r(k) \oplus \overline{m}) = (r, F_r(k) \oplus (0, \ldots, 0)_n) = (r, F_r(k))$$

what reveals $k$.