We analyze the $128$-dimensional Mordell--Weil lattice of a certain elliptic
curve over the rational function field k(t), where k is a finite
field of $2^{12}$ elements. By proving that the elliptic curve has
trivial Tate--Šafarevič group and nonzero rational points of height $22$, we show
that the lattice's density achieves the lower bound derived in our
earlier work. This density is by a considerable factor the largest known
for a sphere packing in dimension 128. We also determine
the kissing number of the lattice, which is by a considerable factor
the largest known for a lattice in this dimension.