prandom_u32_inclusive
this_len = prandom_u32_inclusive(rng, 1, remaining);
div->offset = prandom_u32_inclusive(rng,
cfg->iv_offset = prandom_u32_inclusive(rng, 1,
cfg->key_offset = prandom_u32_inclusive(rng, 1,
vec->ksize = prandom_u32_inclusive(rng, 1, maxkeysize);