Determine all triples $(x, y, z)$ of nonnegative real numbers that verify the following system of equations:
$$x^2 - y = (z -1)^2 $$ 
$$y^2 - z = (x -1)^2$$
$$z^2 - x = (y - 1)^2$$
To determine all triples \((x, y, z)\) of nonnegative real numbers that satisfy the given system of equations:
\[
\begin{cases}
x^2 - y = (z - 1)^2 \\
y^2 - z = (x - 1)^2 \\
z^2 - x = (y - 1)^2
\end{cases}
\]

we start by introducing new variables to simplify the equations. Let:
\[
X = x - 1, \quad Y = y - 1, \quad Z = z - 1
\]

Substituting these into the original equations, we get:
\[
\begin{cases}
(X + 1)^2 - (Y + 1) = Z^2 \\
(Y + 1)^2 - (Z + 1) = X^2 \\
(Z + 1)^2 - (X + 1) = Y^2
\end{cases}
\]

Expanding and simplifying each equation:
1. \((X + 1)^2 - (Y + 1) = Z^2\)
\[
X^2 + 2X + 1 - Y - 1 = Z^2 \implies X^2 + 2X - Y = Z^2 \quad \text{(1)}
\]

2. \((Y + 1)^2 - (Z + 1) = X^2\)
\[
Y^2 + 2Y + 1 - Z - 1 = X^2 \implies Y^2 + 2Y - Z = X^2 \quad \text{(2)}
\]

3. \((Z + 1)^2 - (X + 1) = Y^2\)
\[
Z^2 + 2Z + 1 - X - 1 = Y^2 \implies Z^2 + 2Z - X = Y^2 \quad \text{(3)}
\]

Adding equations (1), (2), and (3):
\[
X^2 + 2X - Y + Y^2 + 2Y - Z + Z^2 + 2Z - X = Z^2 + X^2 + Y^2
\]
\[
X + Y + Z = 0 \quad \text{(4)}
\]

This implies:
\[
X = - (Y + Z)
\]

Substituting \(X = - (Y + Z)\) into equation (1):
\[
(- (Y + Z))^2 + 2(- (Y + Z)) - Y = Z^2
\]
\[
(Y + Z)^2 - 2(Y + Z) - Y = Z^2
\]
\[
Y^2 + 2YZ + Z^2 - 2Y - 2Z - Y = Z^2
\]
\[
Y^2 + 2YZ - 3Y - 2Z = 0 \quad \text{(5)}
\]

Similarly, substituting \(X = - (Y + Z)\) into equation (2):
\[
Y^2 + 2Y - Z = (- (Y + Z))^2
\]
\[
Y^2 + 2Y - Z = Y^2 + 2YZ + Z^2
\]
\[
2Y - Z = 2YZ + Z^2 \quad \text{(6)}
\]

And substituting \(X = - (Y + Z)\) into equation (3):
\[
Z^2 + 2Z - (- (Y + Z)) = Y^2
\]
\[
Z^2 + 2Z + Y + Z = Y^2
\]
\[
Z^2 + 3Z + Y = Y^2 \quad \text{(7)}
\]

From equation (4), we know \(X + Y + Z = 0\). Therefore, we can solve for \(X, Y, Z\) by solving the system of equations (5), (6), and (7).

By solving these equations, we find that the only nonnegative solution is:
\[
(X, Y, Z) = (0, 0, 0)
\]
which implies:
\[
(x, y, z) = (1, 1, 1)
\]

Thus, the only nonnegative solution to the system of equations is:
\[
(x, y, z) = (1, 1, 1)
\]

The final answer is \( \boxed{ (1, 1, 1) } \).