messing around with JWT implementation

src/ArduinoJsonJWT.cpp

@@ -0,0 +1,96 @@
+#include "ArduinoJsonJWT.h"
+
+ArduinoJsonJWT::ArduinoJsonJWT(String secret) : _secret(secret) { }
+
+void ArduinoJsonJWT::setSecret(String secret){
+    _secret = secret;
+}
+
+String ArduinoJsonJWT::sign(String &value) {
+  // create signature
+  Sha256.initHmac((uint8_t*) _secret.c_str(), _secret.length());
+  Sha256.print(value);
+
+  // trim and return
+  return encode(Sha256.resultHmac(), 32);
+}
+
+String ArduinoJsonJWT::decode(unsigned char * value) {
+  // create buffer of approperate length
+  size_t decodedLength = decode_base64_length(value) + 1;
+  char decoded[decodedLength];
+
+  // decode
+  decode_base64(value, (unsigned char *) decoded);
+  decoded[decodedLength-1] = 0;
+
+  // return as arduino string
+  return String(decoded);
+}
+
+String ArduinoJsonJWT::encode(unsigned char * value , int length) {
+  int encodedIndex = encode_base64_length(length);
+
+  // encode
+  char encoded[encodedIndex];
+  encode_base64(value, length, (unsigned char *) encoded);
+
+  // trim padding
+  while (encoded[--encodedIndex] == '=') {
+    encoded[encodedIndex] = 0;
+  }  
+
+  // return as string
+  return String(encoded);
+}
+
+String ArduinoJsonJWT::buildJWT(JsonObject &payload) {
+  // serialize, then encode payload
+  String jwt;
+  serializeJson(payload, jwt);
+  jwt = encode((unsigned char *) jwt.c_str(), jwt.length());
+
+  // add the header to payload
+  jwt = JWT_HEADER + '.' + jwt;
+ 
+  // add signature
+  jwt  += '.' + sign(jwt);
+
+  return jwt;
+}
+
+void ArduinoJsonJWT::parseJWT(String jwt, JsonDocument &jsonDocument) {
+  // clear json document before we begin, jsonDocument wil be null on failure
+  jsonDocument.clear();
+
+  // must be of minimum length or greater
+  if (jwt.length() <= JWT_SIG_SIZE + JWT_HEADER_SIZE + 2) {
+    return;
+  }
+  // must have the correct header and delimiter
+  if (!jwt.startsWith(JWT_HEADER) || jwt.indexOf('.') != JWT_HEADER_SIZE) {
+    return;
+  }
+  // must have signature of correct length
+  int signatureDelimieterIndex = jwt.length() - JWT_SIG_SIZE - 1;
+  if (jwt.lastIndexOf('.') != signatureDelimieterIndex) {
+    return;
+  }
+
+  // signature must be correct
+  String signature = jwt.substring(signatureDelimieterIndex + 1);
+  jwt = jwt.substring(0, signatureDelimieterIndex);
+  if (sign(jwt) != signature){
+    return;
+  }
+
+  // decode payload
+  jwt = jwt.substring(JWT_HEADER_SIZE + 1); 
+  jwt = decode((unsigned char *) jwt.c_str());
+  
+  // parse payload, clearing json document after failure
+  DeserializationError error = deserializeJson(jsonDocument, jwt);
+  if (error != DeserializationError::Ok || !jsonDocument.is<JsonObject>()){
+    jsonDocument.clear();
+  }
+}

src/ArduinoJsonJWT.h

@@ -0,0 +1,34 @@
+#ifndef ArduinoJsonJWT_H
+#define ArduinoJsonJWT_H
+
+#include "sha256.h"
+#include "base64.h"
+
+#include <Arduino.h>
+#include <ArduinoJson.h>
+
+#define JWT_HEADER_SIZE 36
+#define JWT_SIG_SIZE 43
+
+class ArduinoJsonJWT {
+
+private:
+  String _secret;
+
+  // {"alg": "HS256", "typ": "JWT"}
+  const String JWT_HEADER = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9";
+  
+  String sign(String &value);
+  String encode(unsigned char * value, int length);
+  String decode(unsigned char * value);
+
+public:
+  ArduinoJsonJWT(String secret);
+
+  void setSecret(String secret);
+  String buildJWT(JsonObject &payload);
+  void parseJWT(String jwt, JsonDocument &jsonDocument);
+};
+
+
+#endif

src/SecurityManager.cpp

@@ -10,6 +10,14 @@ SecurityManager::SecurityManager(AsyncWebServer* server, FS* fs) : SettingsPersi
   _signInRequestHandler.setMaxContentLength(MAX_SECURITY_MANAGER_SETTINGS_SIZE);
   _signInRequestHandler.onRequest(std::bind(&SecurityManager::signIn, this, std::placeholders::_1, std::placeholders::_2));
   server->addHandler(&_signInRequestHandler);
+
+
+    // sign in request
+  _testVerifiction.setUri(TEST_VERIFICATION_PATH);
+  _testVerifiction.setMethod(HTTP_POST);
+  _testVerifiction.setMaxContentLength(MAX_SECURITY_MANAGER_SETTINGS_SIZE);
+  _testVerifiction.onRequest(std::bind(&SecurityManager::testVerification, this, std::placeholders::_1, std::placeholders::_2));
+  server->addHandler(&_testVerifiction);
 }
 
 SecurityManager::~SecurityManager() {}
@@ -72,15 +80,16 @@ void SecurityManager::signIn(AsyncWebServerRequest *request, JsonDocument &jsonD
       // create JWT
       DynamicJsonDocument _jsonDocument(MAX_JWT_SIZE);      
       JsonObject jwt = _jsonDocument.to<JsonObject>();
-      jwt["user"] = user.getUsername();
+      jwt["username"] = user.getUsername();
       jwt["role"] = user.getRole();
       
       // send JWT response
       AsyncJsonResponse * response = new AsyncJsonResponse(MAX_USERS_SIZE);
       JsonObject jsonObject = response->getRoot();
-      jsonObject["access_token"] = jwtHandler.encodeJWT(jwt);
+      jsonObject["access_token"] = jwtHandler.buildJWT(jwt);
       response->setLength();
       request->send(response);
+      return;
     }
   }
 
@@ -89,6 +98,20 @@ void SecurityManager::signIn(AsyncWebServerRequest *request, JsonDocument &jsonD
   request->send(response);
 }
 
+void SecurityManager::testVerification(AsyncWebServerRequest *request, JsonDocument &jsonDocument){
+  if (jsonDocument.is<JsonObject>()) {    
+    String accessToken =  jsonDocument["access_token"];
+    DynamicJsonDocument parsedJwt(MAX_JWT_SIZE); 
+    if (jwtHandler.parseJWT(accessToken, parsedJwt)){
+      String username = parsedJwt["username"];
+
+    }
+  }
+  // authentication failed
+  AsyncWebServerResponse *response =  request->beginResponse(401);
+  request->send(response);
+}
+
 void SecurityManager::fetchUsers(AsyncWebServerRequest *request) {
   AsyncJsonResponse * response = new AsyncJsonResponse(MAX_USERS_SIZE);
   JsonObject jsonObject = response->getRoot();  
@@ -102,7 +125,7 @@ void SecurityManager::begin() {
   readFromFS();
 
   // configure secret
-  jwtHandler.setPSK(_jwtSecret);
+  jwtHandler.setSecret(_jwtSecret);
 }
 
 User SecurityManager::verifyUser(String jwt) {

src/SecurityManager.h

@@ -6,7 +6,7 @@
 #include <SettingsService.h>
 #include <DNSServer.h>
 #include <IPAddress.h>
-#include <jwt/ArduinoJsonJWT.h>
+#include <ArduinoJsonJWT.h>
 
 #define DEFAULT_JWT_SECRET "esp8266-react"
 
@@ -15,6 +15,7 @@
 #define USERS_PATH "/rest/users"
 #define AUTHENTICATE_PATH "/rest/authenticate"
 #define SIGN_IN_PATH "/rest/signIn"
+#define TEST_VERIFICATION_PATH "/rest/verification"
 
 #define MAX_JWT_SIZE 128
 #define MAX_SECURITY_MANAGER_SETTINGS_SIZE 512
@@ -85,6 +86,7 @@ class SecurityManager :  public SettingsPersistence {
     // server instance
     AsyncWebServer* _server;
     AsyncJsonRequestWebHandler _signInRequestHandler;
+    AsyncJsonRequestWebHandler _testVerifiction;
 
     // access point settings
     String _jwtSecret;
@@ -94,6 +96,7 @@ class SecurityManager :  public SettingsPersistence {
     // endpoint functions
     void fetchUsers(AsyncWebServerRequest *request);
     void signIn(AsyncWebServerRequest *request, JsonDocument &jsonDocument);
+    void testVerification(AsyncWebServerRequest *request, JsonDocument &jsonDocument);
 };
 
 #endif // end SecurityManager_h

src/base64.cpp

@@ -1,3 +1,5 @@
+#include "base64.h"
+
 unsigned char binary_to_base64(unsigned char v) {
   // Capital letters - 'A' is ascii 65 and base64 0
   if(v < 26) return v + 'A';

src/jwt/ArduinoJsonJWT.cpp

@@ -1,50 +0,0 @@
-#include "jwt/ArduinoJsonJWT.h"
-
-ArduinoJsonJWT::ArduinoJsonJWT(String psk) : _psk(psk) { }
-
-void ArduinoJsonJWT::setPSK(String psk){
-    _psk = psk;
-}
-
-String ArduinoJsonJWT::encodeJWT(JsonObject payload) {
-  // serialize payload
-  String serializedPayload;
-  serializeJson(payload, serializedPayload);
-
-  // calculate length of string
-  uint16_t encodedPayloadLength = encode_base64_length(serializedPayload.length());
-
-  // create JWT char array
-  char encodedJWT[BASE_JWT_LENGTH + encodedPayloadLength];
-  unsigned char* ptr = (unsigned char*) encodedJWT;
-
-  // 1 - add the header
-  memcpy(ptr, JWT_HEADER, JWT_HEADER_LENGTH);
-  ptr += JWT_HEADER_LENGTH;
-
-  // 2 - add payload, trim and null terminate
-  *ptr++ = '.';
-  encode_base64((unsigned char*) serializedPayload.c_str(), serializedPayload.length(), ptr);
-  ptr += encodedPayloadLength;
-  while(*(ptr - 1) == '=') {
-    ptr--;
-  }
-  *(ptr) = 0;
-  
-  // ... calculate ...
-  Sha256.initHmac((const unsigned char*)_psk.c_str(), _psk.length());
-  Sha256.print(encodedJWT);
-
-  // 3 - add signature
-  *ptr++ = '.';
-  encode_base64(Sha256.resultHmac(), 32, ptr);
-  ptr += SIGNATURE_LENGTH;
-  while(*(ptr - 1) == '=') {
-    ptr--;
-  }
-  *(ptr) = 0;
-
-  Serial.println(BASE_JWT_LENGTH + encodedPayloadLength);
-  return encodedJWT;
-}
-

src/jwt/ArduinoJsonJWT.h

@@ -1,34 +0,0 @@
-#ifndef ArduinoJsonJWT_H
-#define ArduinoJsonJWT_H
-
-#include "jwt/base64.h"
-#include "jwt/sha256.h"
-#include "jwt/ArduinoJsonJWT.h"
-
-#include <Arduino.h>
-#include <ArduinoJson.h>
-
-class ArduinoJsonJWT {
-
-private:
-  String _psk;
-
-  // {"alg": "HS256", "typ": "JWT"}
-  const char* JWT_HEADER = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9";
-  const uint16_t JWT_HEADER_LENGTH = strlen(JWT_HEADER);
-  const uint16_t SIGNATURE_LENGTH = encode_base64_length(32);  
-
-  // static JWT length is made of:
-  // - the header length
-  // - the signature length
-  // - 2 delimiters, 1 terminator
-  const uint16_t BASE_JWT_LENGTH = JWT_HEADER_LENGTH + SIGNATURE_LENGTH + 3;
-
-public:
-  ArduinoJsonJWT(String psk);
-  void setPSK(String psk);
-  String encodeJWT(JsonObject payload);
-};
-
-
-#endif

src/sha256.cpp

@@ -1,6 +1,7 @@
-#include <string.h>
 #include "sha256.h"
 
+#include <string.h>
+
 uint32_t sha256K[] PROGMEM = {
   0x428a2f98,0x71374491,0xb5c0fbcf,0xe9b5dba5,0x3956c25b,0x59f111f1,0x923f82a4,0xab1c5ed5,
   0xd807aa98,0x12835b01,0x243185be,0x550c7dc3,0x72be5d74,0x80deb1fe,0x9bdc06a7,0xc19bf174,