getkey
oldp->key = getkey("old file", oldp->keygen, oldp->keylen, NULL);
p->key = getkey("new file", p->keygen, p->keylen, NULL);
static bits_t *getkey(const char *, struct keygen *, size_t,
p->key = getkey(dev, p->keygen, p->keylen, NULL);
p->key = getkey(argv[1], p->keygen, p->keylen, &skh);