Let $a,b,c,d$ be selected at random from $Z_q$. Consider the following two distributions $X_1$ and $Y_1$:
$X_1={(r_1\cdot a, r_2\cdot b, r_3\cdot c, (r_1+r_2-r_3)\cdot d)}$ where $r_1,r_2,r_3$ selected random from $Z_q$
$Y_1={(u_1,u_2,u_3,u_4)}$ where $u_1,u_2,u_3,u_4$ selected random from $Z_q$
I have two questions:
- Are these two distributions computationally indistinguishable?
- How should I formally write the proof?
