Since this puzzle depends only on the pre-image resistance of RIPEMD-160 (not on any elliptic curve assumption)

ECDSA also do not rely on an "elliptic curve assumption". They rely on the the Diffie–Hellman assumption. The elliptic curve is only the group on which it is calculated.

bitcoin

Quantum Secure Bitcoin Transaction created without a Hard Fork

029e4c1f1b

> Since this puzzle depends only on the pre-image resistance of RIPEMD-160 (not on any elliptic curve assumption)

ECDSA also do not rely on an "elliptic curve assumption". They rely on the the Diffie–Hellman assumption. The elliptic curve is only the group on which it is calculated.