sshbuf_get_eckey
if ((r = sshbuf_get_eckey(b, ec)) != 0) {
ASSERT_INT_EQ(sshbuf_get_eckey(p1, eck), 0);
sshbuf_get_eckey(p1, eck);
if ((r = sshbuf_get_eckey(b, ec)) != 0)
int sshbuf_get_eckey(struct sshbuf *buf, EC_KEY *v);