ecdh_compute_shared() was changed to immediately delete the ephemeral key after
the shared secret was computed. Therefore, the pointer to the ecdh_t struct
should be zeroed so it won't be freed again when a struct sptps_t is freed.
char shared[ECDH_SHARED_SIZE];
if(!ecdh_compute_shared(s->ecdh, s->hiskex + 1 + 32, shared))
return false;
+ s->ecdh = NULL;
// Generate key material from shared secret.
if(!generate_key_material(s, shared, sizeof shared))