// This method may not be called if the server doesn't send a
	// ServerKeyExchange message.
	processServerKeyExchange(*Config, *clientHelloMsg, *serverHelloMsg, *x509.Certificate, *serverKeyExchangeMsg) error
	generateClientKeyExchange(*Config, *clientHelloMsg, *x509.Certificate) ([]byte, *clientKeyExchangeMsg, error)
}

var errClientKeyExchange = errors.New("tls: invalid ClientKeyExchange message")

		certMsg.certificates = chainToSend.Certificate
		if _, err := hs.c.writeHandshakeRecord(certMsg, &hs.finishedHash); err != nil {
			return err
		}
	}

	preMasterSecret, ckx, err := keyAgreement.generateClientKeyExchange(c.config, hs.hello, c.peerCertificates[0])
	if err != nil {
		c.sendAlert(alertInternalError)
		return err
	}
	if ckx != nil {
		if _, err := hs.c.writeHandshakeRecord(ckx, &hs.finishedHash); err != nil {