Example #1
0
func (h *encHandshake) handleAuthMsg(msg *authMsgV4, prv *ecdsa.PrivateKey) error {
	// Import the remote identity.
	h.initNonce = msg.Nonce[:]
	h.remoteID = msg.InitiatorPubkey
	rpub, err := h.remoteID.Pubkey()
	if err != nil {
		return fmt.Errorf("bad remoteID: %#v", err)
	}
	h.remotePub = ecies.ImportECDSAPublic(rpub)

	// Generate random keypair for ECDH.
	// If a private key is already set, use it instead of generating one (for testing).
	if h.randomPrivKey == nil {
		h.randomPrivKey, err = ecies.GenerateKey(rand.Reader, crypto.S256(), nil)
		if err != nil {
			return err
		}
	}

	// Check the signature.
	token, err := h.staticSharedSecret(prv)
	if err != nil {
		return err
	}
	signedMsg := xor(token, h.initNonce)
	remoteRandomPub, err := secp256k1.RecoverPubkey(signedMsg, msg.Signature[:])
	if err != nil {
		return err
	}
	h.remoteRandomPub, _ = importPublicKey(remoteRandomPub)
	return nil
}
Example #2
0
// makeAuthMsg creates the initiator handshake message.
func (h *encHandshake) makeAuthMsg(prv *ecdsa.PrivateKey, token []byte) (*authMsgV4, error) {
	rpub, err := h.remoteID.Pubkey()
	if err != nil {
		return nil, fmt.Errorf("bad remoteID: %v", err)
	}
	h.remotePub = ecies.ImportECDSAPublic(rpub)
	// Generate random initiator nonce.
	h.initNonce = make([]byte, shaLen)
	if _, err := rand.Read(h.initNonce); err != nil {
		return nil, err
	}
	// Generate random keypair to for ECDH.
	h.randomPrivKey, err = ecies.GenerateKey(rand.Reader, crypto.S256(), nil)
	if err != nil {
		return nil, err
	}

	// Sign known message: static-shared-secret ^ nonce
	token, err = h.staticSharedSecret(prv)
	if err != nil {
		return nil, err
	}
	signed := xor(token, h.initNonce)
	signature, err := crypto.Sign(signed, h.randomPrivKey.ExportECDSA())
	if err != nil {
		return nil, err
	}

	msg := new(authMsgV4)
	copy(msg.Signature[:], signature)
	copy(msg.InitiatorPubkey[:], crypto.FromECDSAPub(&prv.PublicKey)[1:])
	copy(msg.Nonce[:], h.initNonce)
	msg.Version = 4
	return msg, nil
}