compute_digest
digest = compute_digest(ch, ch->hlen);
digest = compute_digest((const char *)ch + ch->pdo, data_len);
header_digest = compute_digest(hdr, hlen);
data_digest = compute_digest(data, data_len);
digest = compute_digest(ch, hlen);
static void compute_digest(struct mkuz_blk *);
compute_digest(oblk);