Suppose all the values and operations are defined over a finite field $\mathbb{F}_p$ where $p$ is a large prime number. Assume all values are non-zero. Here $(z)^{-1}$ denotes multiplicative inverse of value $z$.
We give away the values $v_1$ and $v_2$ to an adversary and ask him to compute their product:
- $v_1=a\cdot z_1$
- $v_2=b \cdot z_2 \cdot (z_1)^{-1}$
So, the adversary computes $v_3= v_1\cdot v_2=a\cdot b \cdot z_2$.
The values $z_i$ are picked uniformly at random from the field. But $a$ and $b$ are fixed values of the field.
Questions:
- Given the three values $v_3, v_1$ and $v_2$ can the adversary learn anything about the fixed values $a$ and $b$ (and the $z_i$ values)? If yes/no Why?
Given the three values $v_3, v_1$ and $v_2$ can the adversary learn anything about the fixed values $a$ and $b$ (and the $z_i$ values)? If yes/no Why?
In other worlds, given the above three values, can the adversary infer anything about $a$ and $b$?
Let $v_1=a\cdot z_1$ and $v_2=(z_1)^{-1}\cdot z_2$.
If we give $v_1$ and $v_2$ to the adversary and ask him to compute their product: $v_3=v_1\cdot v_2=a\cdot z_2$ would it learn the secret value $a$ (and $z_i$ values)?
In other worlds, given the above three values, can the adversary infer anything about $a$ and $b$?
- Let $v_1=a\cdot z_1$ and $v_2=(z_1)^{-1}\cdot z_2$.
If we give $v_1$ and $v_2$ to the adversary and ask him to compute their product: $v_3=v_1\cdot v_2=a\cdot z_2$ would it learn the secret value $a$ (and $z_i$ values)?