File content as of revision 4:cd2dc3e7433f:

/*******************************************************************************
* Copyright (C) 2017 Maxim Integrated Products, Inc., All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* Except as contained in this notice, the name of Maxim Integrated
* Products, Inc. shall not be used except as stated in the Maxim Integrated
* Products, Inc. Branding Policy.
*
* The mere transfer of this software does not imply any licenses
* of trade secrets, proprietary technology, copyrights, patents,
* trademarks, maskwork rights, or any other form of intellectual
* property whatsoever. Maxim Integrated Products, Inc. retains all
* ownership rights.
*******************************************************************************/

#define RAPIDJSON_ENDIAN RAPIDJSON_LITTLEENDIAN
#include <rapidjson/document.h>
#include <rapidjson/writer.h>
#include <rapidjson/stringbuffer.h>

#include <stdint.h>
#include <stdio.h>
#include <cassert>
#include <cstdio>
#include <string>
#include <utility>
#include "Image.hpp"
#include "Text.hpp"
#include "WindowManager.hpp"
#include "ErrorWindow.hpp"
#include "DisplayIdWindow.hpp"
#include "NormalOperationWindow.hpp"
#include "DisplayGraphicWindow.hpp"
#include "HexConversions.hpp"
#include "DS2476.hpp"
#include "SensorNode.hpp"

extern DS2476 coproc;
extern SensorNode sensorNode;
extern std::string webId;

extern "C" {
    void ComputeSHA256(unsigned char* message, short length, unsigned short skipconst,
        unsigned short reverse, unsigned char* digest);
}

static const size_t defaultChunkSize = 256; // Default allocation size for rapidjson.
static const int jsonMaxDecimalPlaces = 2; // Number of decimal places to use when writing JSON.

// Separate multiple JSON commands received on the socket.
// Returns a list of begin and end iterators within the input message.
static std::vector<std::pair<const char *, const char *> > separateCommands(const char * receivedData, size_t receivedDataSize)
{    
    std::vector<std::pair<const char *, const char *> > commands;
    unsigned int counter = 0;
    size_t beginIdx;
    for (size_t i = 0; i < receivedDataSize; i++)
    {
        if (receivedData[i] == '{')
        {
            if (counter == 0)
            {
                beginIdx = i;
            }
            counter++;
        }
        else if (receivedData[i] == '}')
        {
            if (counter > 0)
            {
                counter--;
                if (counter == 0)
                {
                    commands.push_back(std::make_pair(&receivedData[beginIdx], &receivedData[i + 1]));
                }
            }
        }
    }
    return commands;
}

// Adds signature information to an existing JSON document.
static DS2476::CmdResult signData(bool validSignature, const std::vector<uint8_t> & challenge, rapidjson::Document & document)
{
    // Move contents of document to a new location and create an empty object in document.
    rapidjson::Value data(rapidjson::kObjectType);
    data.Swap(document);
    // Convert data to a string and generate a signature from that string.
    rapidjson::StringBuffer dataBuffer;
    rapidjson::Writer<rapidjson::StringBuffer> writer(dataBuffer);
    writer.SetMaxDecimalPlaces(jsonMaxDecimalPlaces);
    data.Accept(writer);
    std::vector<uint8_t> signDataBuffer(dataBuffer.GetString(), dataBuffer.GetString() + dataBuffer.GetLength());
    signDataBuffer.insert(signDataBuffer.end(), challenge.begin(), challenge.end());
    DS2476::Buffer ds2476Buffer(32);
    ComputeSHA256(&signDataBuffer[0], signDataBuffer.size(), false, false, &ds2476Buffer[0]);
    DS2476::CmdResult result = coproc.writeBuffer(ds2476Buffer);
    if (result == DS2476::Success)
    {
        DS2476::Signature signatureBuffer;
        result = coproc.generateEcdsaSignature(DS2476::KeyNumA, signatureBuffer);
        if (result == DS2476::Success)
        {
            if (!validSignature)
                signatureBuffer.r[0]++;
            // Construct the final document with the original data and the generated signature.
            rapidjson::Value signature(rapidjson::kObjectType);
            signature.AddMember("r", rapidjson::Value(byteArrayToHexString(signatureBuffer.r.data(),
                signatureBuffer.r.size()).c_str(), document.GetAllocator()).Move(), document.GetAllocator());
            signature.AddMember("s", rapidjson::Value(byteArrayToHexString(signatureBuffer.s.data(),
                signatureBuffer.s.size()).c_str(), document.GetAllocator()).Move(), document.GetAllocator());
            document.AddMember("data", data, document.GetAllocator());
            document.AddMember("signature", signature, document.GetAllocator());
        }
    }
    return result;
}

// Parse and verify a signed JSON string.
static DS2476::CmdResult verifySignedData(const std::string & verifyData, rapidjson::Document & signedData)
{
    using rapidjson::Value;
    using std::string;
    
    // Parse string and validate object schema.
    signedData.Parse(verifyData.c_str());
    if (!(signedData.IsObject() && signedData.HasMember("data") && signedData.HasMember("signature")))
    {
        signedData.RemoveAllMembers();
        return DS2476::AuthenticationError;
    }
    Value & data = signedData["data"];
    const Value & signature = signedData["signature"];
    if (!(data.IsObject() && signature.IsObject() && signature.HasMember("r") && signature.HasMember("s")))
    {
        signedData.RemoveAllMembers();
        return DS2476::AuthenticationError;
    }
    const Value & signatureR = signature["r"];
    const Value & signatureS = signature["s"];
    if (!(signatureR.IsString() && signatureS.IsString()))
    {
        signedData.RemoveAllMembers();
        return DS2476::AuthenticationError;
    }
    
    // Parse signature.
    std::vector<uint8_t> parsedBytes =
        hexStringToByteArray(std::string(signatureR.GetString(), signatureR.GetStringLength()));
    DS2476::Signature signatureBuffer;
    if (parsedBytes.size() != signatureBuffer.r.size())
    {
        signedData.RemoveAllMembers();
        return DS2476::AuthenticationError;
    }
    std::copy(parsedBytes.begin(), parsedBytes.end(), signatureBuffer.r.begin());
    parsedBytes = hexStringToByteArray(std::string(signatureS.GetString(), signatureS.GetStringLength()));
    if (parsedBytes.size() != signatureBuffer.s.size())
    {
        signedData.RemoveAllMembers();
        return DS2476::AuthenticationError;
    }
    std::copy(parsedBytes.begin(), parsedBytes.end(), signatureBuffer.s.begin());
    
    // Compute hash of the data.
    // Need to use string searching here since there isn't currently a way to access raw elements
    // in rapidjson, and creating another copy of the data might consume too much memory.
    const string rawDataSearch("\"data\":");
    string::size_type rawDataBegin = verifyData.find(rawDataSearch);
    if ((rawDataBegin == string::npos) || ((rawDataBegin + rawDataSearch.size()) >= verifyData.size()))
    {
        signedData.RemoveAllMembers();
        return DS2476::AuthenticationError;
    }
    rawDataBegin += rawDataSearch.size();
    string::size_type rawDataEnd = verifyData.find(",\"signature\"", rawDataBegin);
    if (rawDataEnd == string::npos)
    {
        signedData.RemoveAllMembers();
        return DS2476::AuthenticationError;
    }
    const string::size_type chunkSize = 64;
    for (string::size_type i = rawDataBegin; i < rawDataEnd; i += chunkSize)
    {
        const string::size_type remainingLength = rawDataEnd - i;
        DS2476::CmdResult result = coproc.computeMultiblockHash(i == 0, remainingLength < chunkSize,
            DS2476::Buffer(verifyData.c_str() + i, verifyData.c_str() + i + std::min(remainingLength, chunkSize)));
        if (result != DS2476::Success)
        {
            signedData.RemoveAllMembers();
            return result;
        }
    }
    // Verify signature.
    DS2476::CmdResult result =
        coproc.verifyEcdsaSignature(DS2476::KeyNumC, DS2476::THASH, signatureBuffer);
    if (result != DS2476::Success)
    {
        signedData.RemoveAllMembers();
        return result;
    }
    
    // Strip signing information from document.
    rapidjson::Value swapObject(rapidjson::kObjectType);
    swapObject.Swap(data);
    swapObject.Swap(signedData);
    return result;
}

// Send a JSON document to the server.
static void sendJson(const rapidjson::Value & document, TCPSocket & socket)
{
    rapidjson::StringBuffer buffer;
    rapidjson::Writer<rapidjson::StringBuffer> writer(buffer);
    writer.SetMaxDecimalPlaces(jsonMaxDecimalPlaces);
    document.Accept(writer);
    socket.send(buffer.GetString(), buffer.GetLength());
}

void NormalOperationWindow::sendMessage(const char * message)
{
    rapidjson::MemoryPoolAllocator<> allocator(defaultChunkSize);
    rapidjson::Document document(rapidjson::kObjectType, &allocator);
    document.AddMember("message", rapidjson::StringRef(message), document.GetAllocator());
    sendJson(document, *socket);
}

static std::string getValidSignatureButtonText(bool validSignature)
{
    return validSignature ? "Use invalid sig." : "Use valid sig.";
}

void NormalOperationWindow::showWebId()
{
    if (windowManager() != NULL)
    {
        windowManager()->push(new DisplayIdWindow(DisplayIdWindow::PopupMode));
    }
}

void NormalOperationWindow::toggleValidSignature()
{
    validSignature = !validSignature;
    validSignatureButton.setText(getValidSignatureButtonText(validSignature));
}

NormalOperationWindow::NormalOperationWindow(TCPSocket * socket, Graphic * parent) : Window(parent),
    socket(socket), validSignature(true), lastSensorNodeState(Disconnected),
    lastObjectTemp(0), lastAmbientTemp(0),
    validSignatureButton(getValidSignatureButtonText(validSignature), this),
    showWebIdButton("Show web ID", this)
{
    assert(socket != NULL);
    
    validSignatureButton.setClickedHandler(Button::EventHandler(this, &NormalOperationWindow::toggleValidSignature));
    showWebIdButton.setClickedHandler(Button::EventHandler(this, &NormalOperationWindow::showWebId));
    validSignatureButton.setFocused();
}

NormalOperationWindow::SensorNodeState NormalOperationWindow::detectSensorNode()
{
    SensorNodeState sensorNodeState;
    if (sensorNode.detect())
    {
        bool provisioned;
        if (sensorNode.getProvisioned(provisioned))
        {
            if (provisioned)
            {
                if (sensorNode.authenticate())
                {
                    bool laserEnabled;
                    if (sensorNode.getLaserEnabled(laserEnabled))
                    {
                        sensorNodeState = (laserEnabled ? ValidLaserEnabled : ValidLaserDisabled);
                    }
                    else
                    {
                        sensorNodeState = Disconnected;
                    }
                }
                else
                {
                    sensorNodeState = Invalid;
                }
            }
            else
            {
                bool provisionResult = sensorNode.provision();
                if (provisionResult)
                {
                    // Detect the new state after provisioning.
                    sensorNodeState = detectSensorNode();
                }
                else
                {
                    sensorNodeState = FailedProvision;
                }
            }
        }
        else
        {
            sensorNodeState = Disconnected;
        }
    }
    else
    {
        sensorNodeState = Disconnected;
    }
    return sensorNodeState;
}

NormalOperationWindow::Result NormalOperationWindow::sendStatus(const std::vector<uint8_t> & challenge)
{
    rapidjson::MemoryPoolAllocator<> allocator(defaultChunkSize);
    rapidjson::Document document(rapidjson::kObjectType, &allocator);
    
    // Insert Web ID.
    document.AddMember("id", rapidjson::StringRef(webId.c_str()), document.GetAllocator());
    
    // Insert device public key.
    rapidjson::Value publicKey(rapidjson::kObjectType);
    DS2476::Page page;
    DS2476::CmdResult result = coproc.readMemory(DS2476::PublicKeyAX, page);
    if (result != DS2476::Success)
    {
        if (windowManager() != NULL)
        {
            windowManager()->pop();
            windowManager()->push(new ErrorWindow("Failed to read PublicKeyAX"));
        }
        return WindowsChanged;
    }
    publicKey.AddMember("x", rapidjson::Value(byteArrayToHexString(page.data(), page.size()).c_str(),
        document.GetAllocator()).Move(), document.GetAllocator());
    result = coproc.readMemory(DS2476::PublicKeyAY, page);
    if (result != DS2476::Success)
    {
        if (windowManager() != NULL)
        {
            windowManager()->pop();
            windowManager()->push(new ErrorWindow("Failed to read PublicKeyAY"));
        }
        return WindowsChanged;
    }
    publicKey.AddMember("y", rapidjson::Value(byteArrayToHexString(page.data(), page.size()).c_str(),
        document.GetAllocator()).Move(), document.GetAllocator());
    document.AddMember("publicKey", publicKey, document.GetAllocator());

    // Insert device certificate.
    rapidjson::Value certificate(rapidjson::kObjectType);
    result = coproc.readMemory(DS2476::UserData14, page);
    if (result != DS2476::Success)
    {
        if (windowManager() != NULL)
        {
            windowManager()->pop();
            windowManager()->push(new ErrorWindow("Failed to read UserData14"));
        }
        return WindowsChanged;
    }
    certificate.AddMember("r", rapidjson::Value(byteArrayToHexString(page.data(), page.size()).c_str(),
        document.GetAllocator()).Move(), document.GetAllocator());
    result = coproc.readMemory(DS2476::UserData15, page);
    if (result != DS2476::Success)
    {
        if (windowManager() != NULL)
        {
            windowManager()->pop();
            windowManager()->push(new ErrorWindow("Failed to read UserData15"));
        }
        return WindowsChanged;
    }
    certificate.AddMember("s", rapidjson::Value(byteArrayToHexString(page.data(), page.size()).c_str(),
        document.GetAllocator()).Move(), document.GetAllocator());
    document.AddMember("certificate", certificate, document.GetAllocator());
    
    // Sign data and transmit to server.
    result = signData(validSignature, challenge, document);
    if (result != DS2476::Success)
    {
        if (windowManager() != NULL)
        {
            windowManager()->pop();
            windowManager()->push(new ErrorWindow("Failed to sign data"));
        }
        return WindowsChanged;
    }
    sendJson(document, *socket);
    return NoChange;
}

NormalOperationWindow::Result NormalOperationWindow::sendObjectTemp(const std::vector<uint8_t> & challenge)
{
    rapidjson::MemoryPoolAllocator<> allocator(defaultChunkSize);
    rapidjson::Document document(rapidjson::kObjectType, &allocator);
    
    // Read object temperatue and add to document.
    double objectTemp;
    bool sensorResult = sensorNode.readTemp(SensorNode::ObjectTemp, objectTemp);
    if (!sensorResult)
    {
        if (windowManager() != NULL)
        {
            windowManager()->pop();
            windowManager()->push(new ErrorWindow("Failed to read object temperature"));
        }
        return WindowsChanged;
    }
    document.AddMember("objectTemp", objectTemp, document.GetAllocator());
    
    // Sign data and transmit to server.
    DS2476::CmdResult coprocResult = signData(validSignature, challenge, document);
    if (coprocResult != DS2476::Success)
    {
        if (windowManager() != NULL)
        {
            windowManager()->pop();
            windowManager()->push(new ErrorWindow("Failed to sign data"));
        }
        return WindowsChanged;
    }
    sendJson(document, *socket);

    lastObjectTemp = objectTemp;
    return NoChange;
}

NormalOperationWindow::Result NormalOperationWindow::sendAmbientTemp(const std::vector<uint8_t> & challenge)
{
    rapidjson::MemoryPoolAllocator<> allocator(defaultChunkSize);
    rapidjson::Document document(rapidjson::kObjectType, &allocator);
    
    // Read ambient temperatue and add to document.
    double ambientTemp;
    bool sensorResult = sensorNode.readTemp(SensorNode::AmbientTemp, ambientTemp);
    if (!sensorResult)
    {
        if (windowManager() != NULL)
        {
            windowManager()->pop();
            windowManager()->push(new ErrorWindow("Failed to read ambient temperature"));
        }
        return WindowsChanged;
    }
    document.AddMember("ambientTemp", ambientTemp, document.GetAllocator());
    
    // Sign data and transmit to server.
    DS2476::CmdResult coprocResult = signData(validSignature, challenge, document);
    if (coprocResult != DS2476::Success)
    {
        if (windowManager() != NULL)
        {
            windowManager()->pop();
            windowManager()->push(new ErrorWindow("Failed to sign data"));
        }
        return WindowsChanged;
    }
    sendJson(document, *socket);
    
    lastAmbientTemp = ambientTemp;
    return NoChange;
}

void NormalOperationWindow::displayImage(const std::vector<uint8_t> & imageData)
{
    const unsigned int width = 64;
    const unsigned int height = imageData.size() / (width / Bitmap::pixelsPerSegment);
    if (windowManager() != NULL)
    {
        windowManager()->push(
            new DisplayGraphicWindow(
                new Image(Bitmap(width, height, &imageData[0], Bitmap::ScanLineFormat))
            )
        );
    }
}

NormalOperationWindow::Result NormalOperationWindow::processReceivedData(size_t recvBufSize)
{
    // Separate commands and process each one.
    std::vector<std::pair<const char *, const char *> > commands = separateCommands(recvBuf, recvBufSize);
    for (std::vector<std::pair<const char *, const char *> >::const_iterator it = commands.begin(); it != commands.end(); it++)
    {                                                         
        rapidjson::MemoryPoolAllocator<> allocator(defaultChunkSize);
        rapidjson::Document data(&allocator);
        // Verify command signature.
        DS2476::CmdResult verifySignedResult = verifySignedData(std::string(it->first, it->second), data);
        switch (verifySignedResult)
        {
        case DS2476::Success: // Command passed authentication.
            {
                // Verify command schema.
                sendMessage("Received data is authentic");
                if (data.IsObject() && data.HasMember("command"))
                {
                    const rapidjson::Value & command = data["command"];
                    if (command.IsString())
                    {
                        // Parse challenge if included.
                        std::vector<uint8_t> challengeData;
                        if (data.HasMember("challenge"))
                        {
                            const rapidjson::Value & challenge = data["challenge"];
                            if (challenge.IsString())
                            {
                                challengeData =
                                    hexStringToByteArray(std::string(challenge.GetString(), challenge.GetStringLength()));
                            }
                        }
                        
                        // Execute the command.
                        if (command == "getStatus")
                        {
                            Result result = sendStatus(challengeData);
                            if (result != NoChange)
                                return result;
                        }
                        else if (command == "readObjectTemp")
                        {
                            if ((lastSensorNodeState == ValidLaserDisabled) || (lastSensorNodeState == ValidLaserEnabled))
                            {
                                Result result = sendObjectTemp(challengeData);
                                if (result != NoChange)
                                    return result;
                                invalidateRegion();
                            }
                        }
                        else if (command == "readAmbientTemp")
                        {
                            if ((lastSensorNodeState == ValidLaserDisabled) || (lastSensorNodeState == ValidLaserEnabled))
                            {
                                Result result = sendAmbientTemp(challengeData);
                                if (result != NoChange)
                                    return result;
                                invalidateRegion();
                            }
                        }
                        else if (command == "enableModule")
                        {
                            if (lastSensorNodeState == ValidLaserDisabled)
                            {
                                if (sensorNode.setLaserEnabled(true,
                                    SensorNode::PrintHandler(this, &NormalOperationWindow::sendMessage)))
                                {
                                    lastSensorNodeState = ValidLaserEnabled;
                                    invalidateRegion();
                                }
                            }
                        }
                        else if (command == "disableModule")
                        {
                            if (lastSensorNodeState == ValidLaserEnabled)
                            {
                                if (sensorNode.setLaserEnabled(false,
                                    SensorNode::PrintHandler(this, &NormalOperationWindow::sendMessage)))
                                {
                                    lastSensorNodeState = ValidLaserDisabled;
                                    invalidateRegion();
                                }
                            }
                        }
                        else if (command == "displayImage")
                        {
                            if (data.HasMember("image"))
                            {
                                const rapidjson::Value & image = data["image"];
                                if (image.IsString())
                                {
                                    displayImage(
                                        hexStringToByteArray(
                                            std::string(image.GetString(), image.GetStringLength())
                                        )
                                    );
                                    return WindowsChanged;
                                }
                            }
                        }
                    }
                }
            }
            break;
            
        case DS2476::AuthenticationError: // Command failed authentication.
            {
                const char message[] = "Received data is not authentic";
                sendMessage(message);
                Text * messageText = new Text(message);
                messageText->setWordWrap(true);
                if (windowManager() != NULL)
                {
                    windowManager()->push(new DisplayGraphicWindow(messageText));
                }
            }
            return WindowsChanged;
            
        default: // Hardware error occurred.
            {
                const char message[] = "Unable to veify received data";
                sendMessage(message);
                if (windowManager() != NULL)
                {
                    windowManager()->push(new ErrorWindow(message));
                }
            }
            return WindowsChanged;
        }
    }
    return NoChange;
}

void NormalOperationWindow::doLayout()
{
    showWebIdButton.setWidth(width());
    showWebIdButton.setHeight(showWebIdButton.preferredHeight());
    showWebIdButton.setX(0);
    showWebIdButton.setY(height() - showWebIdButton.height());
    validSignatureButton.setWidth(width());
    validSignatureButton.setHeight(validSignatureButton.preferredHeight());
    validSignatureButton.setX(0);
    validSignatureButton.setY(showWebIdButton.y() - validSignatureButton.height() - 1);
}

Bitmap NormalOperationWindow::render() const
{
    // Format current status text.
    std::string sensorNodeStateText;
    switch (lastSensorNodeState)
    {
    case Disconnected:
        sensorNodeStateText = "Disconnected";
        break;
        
    case Invalid:
        sensorNodeStateText = "Invalid";
        break;
        
    case ValidLaserDisabled:
    case ValidLaserEnabled:
        sensorNodeStateText = "Valid";
        break;
        
    case FailedProvision:
        break;
    }
    
    char displayString[100];
    snprintf(displayString, sizeof(displayString) / sizeof(displayString[0]),
        "Object temp: %.2f\nAmbient temp: %.2f\nSensor node: %s",
        lastObjectTemp, lastAmbientTemp, sensorNodeStateText.c_str());
    
    Bitmap bitmap(width(), height());
    Text description((std::string(displayString)));
    description.update();
    bitmap.overlay(description.render(), description.x(), description.y());
    bitmap.overlay(validSignatureButton.render(), validSignatureButton.x(), validSignatureButton.y());
    bitmap.overlay(showWebIdButton.render(), showWebIdButton.x(), showWebIdButton.y());
    return bitmap;
}

void NormalOperationWindow::doPostLayout()
{           
    // Detect sensor node.
    SensorNodeState sensorNodeState = detectSensorNode();
    if (sensorNodeState == FailedProvision)
    {
        if (windowManager() != NULL)
        {
            windowManager()->pop();
            windowManager()->push(new ErrorWindow("Sensor node provision failed"));
        }
        return;
    }
    if (sensorNodeState != lastSensorNodeState)
    {
        lastSensorNodeState = sensorNodeState;
        invalidateRegion();
    }
    
    // Process socket data.
    int recvResult = socket->recv(recvBuf, sizeof(recvBuf) / sizeof(recvBuf[0]));
    if (recvResult > 0)
    {
        std::printf("%*s\n", recvResult, recvBuf);
        Result result = processReceivedData(recvResult);
        if (result != NoChange)
            return;
    }
    else if (recvResult != NSAPI_ERROR_WOULD_BLOCK)
    {
        if (windowManager() != NULL)
        {
            windowManager()->pop();
            windowManager()->push(new ErrorWindow("Socket recieve failed"));
        }
        return;
    }
}

bool NormalOperationWindow::doProcessKey(Key key)
{
    bool handled;
    switch (key)
    {
    case UpKey:
        validSignatureButton.setFocused();
        handled = true;
        break;
        
    case DownKey:
        showWebIdButton.setFocused();
        handled = true;
        break;
        
    default:
        handled = false;
        break;
    }
    return handled;
}