sshbuf_put_bignum2_bytes
r = sshbuf_put_bignum2_bytes(out, shared_key, CURVE25519_SIZE);
r = sshbuf_put_bignum2_bytes(buf, blob, len);
ASSERT_INT_EQ(sshbuf_put_bignum2_bytes(p1, NULL, 0), 0);
ASSERT_INT_EQ(sshbuf_put_bignum2_bytes(p1, bn1, sizeof(bn1)), 0);
ASSERT_INT_EQ(sshbuf_put_bignum2_bytes(p1, bn2+2, sizeof(bn2)-2), 0);
ASSERT_INT_EQ(sshbuf_put_bignum2_bytes(p1, bn2, sizeof(bn2)), 0);
ASSERT_INT_EQ(sshbuf_put_bignum2_bytes(p1, bn3+1, sizeof(bn3)-1), 0);
ASSERT_INT_EQ(sshbuf_put_bignum2_bytes(p1, bn3, sizeof(bn3)), 0);
if ((r = sshbuf_put_bignum2_bytes(inner_sig,
(r = sshbuf_put_bignum2_bytes(inner_sig,
int sshbuf_put_bignum2_bytes(struct sshbuf *buf, const void *v, size_t len);