How to encrypt the truth table in garbled circuits? I'm learning about garbled circuits, and I'm using the following tutorial: Yao's Protocol.

I have a questions regarding to construction (encryption) of truth table in garbled circuits.

Slide 14 says: 


  For each wire x, y, z, specify two random values, corresponding
  to 0 and 1.


So I picked:

(k_x0, k_x1) = 1, 0
(k_y0, k_y1) = 0, 1
(k_z0, k_z1) = 1, 0


Then,


  We need to “associate” (k_z0, k_z1) with (k_x0, k_x1, k_y0, k_y1).


Here's my table according to the values in slide 16.

x | y | z | GCT
----------------
1 | 0 | 1 |  ?
1 | 1 | 1 |  ?
0 | 0 | 1 |  ?
0 | 1 | 0 |  ?


However, I can't figure out what should GCT values be?
How should those values be calculated?
Yao, encodes AND curcuit as;


the $x$ values as $k_x^0,k_x^1$,
the $y$ values as $k_y^0,k_y^1$,
the $z$ values as $z_k^0,z_k^1$.


Here the upper script represents 0 or 1.

\begin{array}{|c|}
\hline GCT \\\hline
  E_{k_x^0}(E_{k_y^0}(k_z^0))  &amp;  \\\hline
  E_{k_x^0}(E_{k_y^1}(k_z^0))  &amp;  \\\hline
  E_{k_x^1}(E_{k_y^0}(k_z^0))  &amp;  \\\hline
  E_{k_x^1}(E_{k_y^1}(k_z^1))  &amp;  \\\hline
\end{array}

Where $E$ is Symmetric Encryption Scheme, and in these schemes Block Ciphers can be utilized. One can use Asymmetric Encryption schemes but that will be slow, and non-standard.

so, given to keys, only one of the rows can be decrypted correctly.