Expand description
Constants required for the ECC chip.
Constants
Window size for fixed-base scalar multiplication
$2^{FIXED_BASE_WINDOW_SIZE
}$
Number of windows for a full-width scalar
Number of windows for a short signed scalar
Functions
For each window, we interpolate the $x$-coordinate. Here, we pre-compute and store the coefficients of the interpolation polynomial.
For each window, $z$ is a field element such that for each point $(x, y)$ in the window:
test_lagrange_coeffs
test-dependencies
Test that Lagrange interpolation coefficients reproduce the correct x-coordinate for each fixed-base multiple in each window.
test_zs_and_us
test-dependencies
Test that the z-values and u-values satisfy the conditions: 1. z + y = u^2, 2. z - y is not a square for the y-coordinate of each fixed-base multiple in each window.