Exemplo n.º 1
0
func newClientArgs(args *pt.Args) (ca *ssClientArgs, err error) {
	ca = &ssClientArgs{}
	if ca.kB, err = parsePasswordArg(args); err != nil {
		return nil, err
	}

	// Generate the client keypair before opening a connection since the time
	// taken is visible to an adversary.  This key might not end up being used
	// if a session ticket is present, but this doesn't take that long.
	if ca.sessionKey, err = uniformdh.GenerateKey(csrand.Reader); err != nil {
		return nil, err
	}
	return
}
Exemplo n.º 2
0
func (conn *obfs3Conn) handshake() error {
	// The party who opens the connection is the 'initiator'; the one who
	// accepts it is the 'responder'.  Each begins by generating a
	// UniformDH keypair, and a random number PADLEN in [0, MAX_PADDING/2].
	// Both parties then send:
	//
	//  PUB_KEY | WR(PADLEN)
	privateKey, err := uniformdh.GenerateKey(csrand.Reader)
	if err != nil {
		return err
	}
	padLen := csrand.IntRange(0, maxPadding/2)
	blob := make([]byte, uniformdh.Size+padLen)
	publicKey, err := privateKey.PublicKey.Bytes()
	if err != nil {
		return err
	}
	copy(blob[0:], publicKey)
	if err := csrand.Bytes(blob[uniformdh.Size:]); err != nil {
		return err
	}
	if _, err := conn.Conn.Write(blob); err != nil {
		return err
	}

	// Read the public key from the peer.
	rawPeerPublicKey := make([]byte, uniformdh.Size)
	if _, err := io.ReadFull(conn.Conn, rawPeerPublicKey); err != nil {
		return err
	}
	var peerPublicKey uniformdh.PublicKey
	if err := peerPublicKey.SetBytes(rawPeerPublicKey); err != nil {
		return err
	}

	// After retrieving the public key of the other end, each party
	// completes the DH key exchange and generates a shared-secret for the
	// session (named SHARED_SECRET).
	sharedSecret, err := uniformdh.Handshake(privateKey, &peerPublicKey)
	if err != nil {
		return err
	}
	if err := conn.kdf(sharedSecret); err != nil {
		return err
	}

	return nil
}