/*
* Copyright 2016 Red Hat, Inc. and/or its affiliates
* and other contributors as indicated by the @author tags.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.keycloak.protocol.oidc.endpoints;
import org.jboss.logging.Logger;
import org.jboss.resteasy.spi.HttpRequest;
import org.jboss.resteasy.spi.ResteasyProviderFactory;
import org.keycloak.OAuth2Constants;
import org.keycloak.OAuthErrorException;
import org.keycloak.authentication.AuthenticationProcessor;
import org.keycloak.common.ClientConnection;
import org.keycloak.common.constants.ServiceAccountConstants;
import org.keycloak.common.util.Base64Url;
import org.keycloak.constants.AdapterConstants;
import org.keycloak.events.Details;
import org.keycloak.events.Errors;
import org.keycloak.events.EventBuilder;
import org.keycloak.events.EventType;
import org.keycloak.models.AuthenticationFlowModel;
import org.keycloak.models.AuthenticatedClientSessionModel;
import org.keycloak.models.ClientModel;
import org.keycloak.models.KeycloakSession;
import org.keycloak.models.RealmModel;
import org.keycloak.models.UserModel;
import org.keycloak.models.UserSessionModel;
import org.keycloak.protocol.oidc.OIDCLoginProtocol;
import org.keycloak.protocol.oidc.TokenManager;
import org.keycloak.protocol.oidc.utils.AuthorizeClientUtil;
import org.keycloak.representations.AccessToken;
import org.keycloak.representations.AccessTokenResponse;
import org.keycloak.services.ErrorResponseException;
import org.keycloak.services.ServicesLogger;
import org.keycloak.services.Urls;
import org.keycloak.services.managers.AuthenticationManager;
import org.keycloak.services.managers.AuthenticationSessionManager;
import org.keycloak.services.managers.ClientManager;
import org.keycloak.services.managers.ClientSessionCode;
import org.keycloak.services.managers.RealmManager;
import org.keycloak.services.resources.Cors;
import org.keycloak.sessions.AuthenticationSessionModel;
import javax.ws.rs.OPTIONS;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.HttpHeaders;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.UriInfo;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.security.MessageDigest;
/**
* @author <a href="mailto:sthorger@redhat.com">Stian Thorgersen</a>
*/
public class TokenEndpoint {
private static final Logger logger = Logger.getLogger(TokenEndpoint.class);
private MultivaluedMap<String, String> formParams;
private ClientModel client;
private Map<String, String> clientAuthAttributes;
private enum Action {
AUTHORIZATION_CODE, REFRESH_TOKEN, PASSWORD, CLIENT_CREDENTIALS
}
// https://tools.ietf.org/html/rfc7636#section-4.2
private static final Pattern VALID_CODE_VERIFIER_PATTERN = Pattern.compile("^[0-9a-zA-Z\\-\\.~_]+$");
@Context
private KeycloakSession session;
@Context
private HttpRequest request;
@Context
private HttpHeaders headers;
@Context
private UriInfo uriInfo;
@Context
private ClientConnection clientConnection;
private final TokenManager tokenManager;
private final RealmModel realm;
private final EventBuilder event;
private Action action;
private String grantType;
public TokenEndpoint(TokenManager tokenManager, RealmModel realm, EventBuilder event) {
this.tokenManager = tokenManager;
this.realm = realm;
this.event = event;
}
@POST
public Response build() {
formParams = request.getDecodedFormParameters();
grantType = formParams.getFirst(OIDCLoginProtocol.GRANT_TYPE_PARAM);
checkSsl();
checkRealm();
checkGrantType();
checkClient();
switch (action) {
case AUTHORIZATION_CODE:
return buildAuthorizationCodeAccessTokenResponse();
case REFRESH_TOKEN:
return buildRefreshToken();
case PASSWORD:
return buildResourceOwnerPasswordCredentialsGrant();
case CLIENT_CREDENTIALS:
return buildClientCredentialsGrant();
}
throw new RuntimeException("Unknown action " + action);
}
@Path("introspect")
public Object introspect() {
TokenIntrospectionEndpoint tokenIntrospectionEndpoint = new TokenIntrospectionEndpoint(this.realm, this.event);
ResteasyProviderFactory.getInstance().injectProperties(tokenIntrospectionEndpoint);
return tokenIntrospectionEndpoint;
}
@OPTIONS
public Response preflight() {
if (logger.isDebugEnabled()) {
logger.debugv("CORS preflight from: {0}", headers.getRequestHeaders().getFirst("Origin"));
}
return Cors.add(request, Response.ok()).auth().preflight().build();
}
private void checkSsl() {
if (!uriInfo.getBaseUri().getScheme().equals("https") && realm.getSslRequired().isRequired(clientConnection)) {
throw new ErrorResponseException(OAuthErrorException.INVALID_REQUEST, "HTTPS required", Response.Status.FORBIDDEN);
}
}
private void checkRealm() {
if (!realm.isEnabled()) {
throw new ErrorResponseException("access_denied", "Realm not enabled", Response.Status.FORBIDDEN);
}
}
private void checkClient() {
AuthorizeClientUtil.ClientAuthResult clientAuth = AuthorizeClientUtil.authorizeClient(session, event);
client = clientAuth.getClient();
clientAuthAttributes = clientAuth.getClientAuthAttributes();
if (client.isBearerOnly()) {
throw new ErrorResponseException(OAuthErrorException.INVALID_CLIENT, "Bearer-only not allowed", Response.Status.BAD_REQUEST);
}
}
private void checkGrantType() {
if (grantType == null) {
throw new ErrorResponseException(OAuthErrorException.INVALID_REQUEST, "Missing form parameter: " + OIDCLoginProtocol.GRANT_TYPE_PARAM, Response.Status.BAD_REQUEST);
}
if (grantType.equals(OAuth2Constants.AUTHORIZATION_CODE)) {
event.event(EventType.CODE_TO_TOKEN);
action = Action.AUTHORIZATION_CODE;
} else if (grantType.equals(OAuth2Constants.REFRESH_TOKEN)) {
event.event(EventType.REFRESH_TOKEN);
action = Action.REFRESH_TOKEN;
} else if (grantType.equals(OAuth2Constants.PASSWORD)) {
event.event(EventType.LOGIN);
action = Action.PASSWORD;
} else if (grantType.equals(OAuth2Constants.CLIENT_CREDENTIALS)) {
event.event(EventType.CLIENT_LOGIN);
action = Action.CLIENT_CREDENTIALS;
} else {
throw new ErrorResponseException(Errors.INVALID_REQUEST, "Invalid " + OIDCLoginProtocol.GRANT_TYPE_PARAM, Response.Status.BAD_REQUEST);
}
event.detail(Details.GRANT_TYPE, grantType);
}
public Response buildAuthorizationCodeAccessTokenResponse() {
String code = formParams.getFirst(OAuth2Constants.CODE);
if (code == null) {
event.error(Errors.INVALID_CODE);
throw new ErrorResponseException(OAuthErrorException.INVALID_REQUEST, "Missing parameter: " + OAuth2Constants.CODE, Response.Status.BAD_REQUEST);
}
String[] parts = code.split("\\.");
if (parts.length == 4) {
event.detail(Details.CODE_ID, parts[2]);
}
ClientSessionCode.ParseResult<AuthenticatedClientSessionModel> parseResult = ClientSessionCode.parseResult(code, session, realm, AuthenticatedClientSessionModel.class);
if (parseResult.isAuthSessionNotFound() || parseResult.isIllegalHash()) {
event.error(Errors.INVALID_CODE);
// Attempt to use same code twice should invalidate existing clientSession
AuthenticatedClientSessionModel clientSession = parseResult.getClientSession();
if (clientSession != null) {
clientSession.setUserSession(null);
}
throw new ErrorResponseException(OAuthErrorException.INVALID_GRANT, "Code not valid", Response.Status.BAD_REQUEST);
}
AuthenticatedClientSessionModel clientSession = parseResult.getClientSession();
if (!parseResult.getCode().isValid(AuthenticatedClientSessionModel.Action.CODE_TO_TOKEN.name(), ClientSessionCode.ActionType.CLIENT)) {
event.error(Errors.INVALID_CODE);
throw new ErrorResponseException(OAuthErrorException.INVALID_GRANT, "Code is expired", Response.Status.BAD_REQUEST);
}
// TODO: This shouldn't be needed to write into the AuthenticatedClientSessionModel itself
parseResult.getCode().setAction(null);
// TODO: Maybe rather create userSession even at this stage?
UserSessionModel userSession = clientSession.getUserSession();
if (userSession == null) {
event.error(Errors.USER_SESSION_NOT_FOUND);
throw new ErrorResponseException(OAuthErrorException.INVALID_GRANT, "User session not found", Response.Status.BAD_REQUEST);
}
UserModel user = userSession.getUser();
if (user == null) {
event.error(Errors.USER_NOT_FOUND);
throw new ErrorResponseException(OAuthErrorException.INVALID_GRANT, "User not found", Response.Status.BAD_REQUEST);
}
if (!user.isEnabled()) {
event.error(Errors.USER_DISABLED);
throw new ErrorResponseException(OAuthErrorException.INVALID_GRANT, "User disabled", Response.Status.BAD_REQUEST);
}
event.user(userSession.getUser());
event.session(userSession.getId());
String redirectUri = clientSession.getNote(OIDCLoginProtocol.REDIRECT_URI_PARAM);
String formParam = formParams.getFirst(OAuth2Constants.REDIRECT_URI);
if (redirectUri != null && !redirectUri.equals(formParam)) {
event.error(Errors.INVALID_CODE);
throw new ErrorResponseException(OAuthErrorException.INVALID_GRANT, "Incorrect redirect_uri", Response.Status.BAD_REQUEST);
}
if (!client.getClientId().equals(clientSession.getClient().getClientId())) {
event.error(Errors.INVALID_CODE);
throw new ErrorResponseException(OAuthErrorException.INVALID_GRANT, "Auth error", Response.Status.BAD_REQUEST);
}
if (!client.isStandardFlowEnabled()) {
event.error(Errors.NOT_ALLOWED);
throw new ErrorResponseException(OAuthErrorException.INVALID_GRANT, "Client not allowed to exchange code", Response.Status.BAD_REQUEST);
}
if (!AuthenticationManager.isSessionValid(realm, userSession)) {
event.error(Errors.USER_SESSION_NOT_FOUND);
throw new ErrorResponseException(OAuthErrorException.INVALID_GRANT, "Session not active", Response.Status.BAD_REQUEST);
}
// https://tools.ietf.org/html/rfc7636#section-4.6
String codeVerifier = formParams.getFirst(OAuth2Constants.CODE_VERIFIER);
String codeChallenge = clientSession.getNote(OIDCLoginProtocol.CODE_CHALLENGE_PARAM);
String codeChallengeMethod = clientSession.getNote(OIDCLoginProtocol.CODE_CHALLENGE_METHOD_PARAM);
String authUserId = user.getId();
String authUsername = user.getUsername();
if (authUserId == null) {
authUserId = "unknown";
}
if (authUsername == null) {
authUsername = "unknown";
}
if (codeChallenge != null && codeVerifier == null) {
logger.warnf("PKCE code verifier not specified, authUserId = %s, authUsername = %s", authUserId, authUsername);
event.error(Errors.CODE_VERIFIER_MISSING);
throw new ErrorResponseException(OAuthErrorException.INVALID_GRANT, "PKCE code verifier not specified", Response.Status.BAD_REQUEST);
}
if (codeChallenge != null) {
// based on whether code_challenge has been stored at corresponding authorization code request previously
// decide whether this client(RP) supports PKCE
if (!isValidPkceCodeVerifier(codeVerifier)) {
logger.infof("PKCE invalid code verifier");
event.error(Errors.INVALID_CODE_VERIFIER);
throw new ErrorResponseException(OAuthErrorException.INVALID_GRANT, "PKCE invalid code verifier", Response.Status.BAD_REQUEST);
}
logger.debugf("PKCE supporting Client, codeVerifier = %s", codeVerifier);
String codeVerifierEncoded = codeVerifier;
try {
// https://tools.ietf.org/html/rfc7636#section-4.2
// plain or S256
if (codeChallengeMethod != null && codeChallengeMethod.equals(OAuth2Constants.PKCE_METHOD_S256)) {
logger.debugf("PKCE codeChallengeMethod = %s", codeChallengeMethod);
codeVerifierEncoded = generateS256CodeChallenge(codeVerifier);
} else {
logger.debug("PKCE codeChallengeMethod is plain");
codeVerifierEncoded = codeVerifier;
}
} catch (Exception nae) {
logger.infof("PKCE code verification failed, not supported algorithm specified");
event.error(Errors.PKCE_VERIFICATION_FAILED);
throw new ErrorResponseException(OAuthErrorException.INVALID_GRANT, "PKCE code verification failed, not supported algorithm specified", Response.Status.BAD_REQUEST);
}
if (!codeChallenge.equals(codeVerifierEncoded)) {
logger.warnf("PKCE verification failed. authUserId = %s, authUsername = %s", authUserId, authUsername);
event.error(Errors.PKCE_VERIFICATION_FAILED);
throw new ErrorResponseException(OAuthErrorException.INVALID_GRANT, "PKCE verification failed", Response.Status.BAD_REQUEST);
} else {
logger.debugf("PKCE verification success. codeVerifierEncoded = %s, codeChallenge = %s", codeVerifierEncoded, codeChallenge);
}
}
updateClientSession(clientSession);
updateUserSessionFromClientAuth(userSession);
AccessToken token = tokenManager.createClientAccessToken(session, parseResult.getCode().getRequestedRoles(), realm, client, user, userSession, clientSession);
AccessTokenResponse res = tokenManager.responseBuilder(realm, client, event, session, userSession, clientSession)
.accessToken(token)
.generateIDToken()
.generateRefreshToken().build();
event.success();
return Cors.add(request, Response.ok(res).type(MediaType.APPLICATION_JSON_TYPE)).auth().allowedOrigins(uriInfo, client).allowedMethods("POST").exposedHeaders(Cors.ACCESS_CONTROL_ALLOW_METHODS).build();
}
public Response buildRefreshToken() {
String refreshToken = formParams.getFirst(OAuth2Constants.REFRESH_TOKEN);
if (refreshToken == null) {
throw new ErrorResponseException(OAuthErrorException.INVALID_REQUEST, "No refresh token", Response.Status.BAD_REQUEST);
}
AccessTokenResponse res;
try {
TokenManager.RefreshResult result = tokenManager.refreshAccessToken(session, uriInfo, clientConnection, realm, client, refreshToken, event, headers);
res = result.getResponse();
if (!result.isOfflineToken()) {
UserSessionModel userSession = session.sessions().getUserSession(realm, res.getSessionState());
AuthenticatedClientSessionModel clientSession = userSession.getAuthenticatedClientSessions().get(client.getId());
updateClientSession(clientSession);
updateUserSessionFromClientAuth(userSession);
}
} catch (OAuthErrorException e) {
event.error(Errors.INVALID_TOKEN);
throw new ErrorResponseException(e.getError(), e.getDescription(), Response.Status.BAD_REQUEST);
}
event.success();
return Cors.add(request, Response.ok(res, MediaType.APPLICATION_JSON_TYPE)).auth().allowedOrigins(uriInfo, client).allowedMethods("POST").exposedHeaders(Cors.ACCESS_CONTROL_ALLOW_METHODS).build();
}
private void updateClientSession(AuthenticatedClientSessionModel clientSession) {
if(clientSession == null) {
ServicesLogger.LOGGER.clientSessionNull();
return;
}
String adapterSessionId = formParams.getFirst(AdapterConstants.CLIENT_SESSION_STATE);
if (adapterSessionId != null) {
String adapterSessionHost = formParams.getFirst(AdapterConstants.CLIENT_SESSION_HOST);
logger.debugf("Adapter Session '%s' saved in ClientSession for client '%s'. Host is '%s'", adapterSessionId, client.getClientId(), adapterSessionHost);
event.detail(AdapterConstants.CLIENT_SESSION_STATE, adapterSessionId);
clientSession.setNote(AdapterConstants.CLIENT_SESSION_STATE, adapterSessionId);
event.detail(AdapterConstants.CLIENT_SESSION_HOST, adapterSessionHost);
clientSession.setNote(AdapterConstants.CLIENT_SESSION_HOST, adapterSessionHost);
}
}
private void updateUserSessionFromClientAuth(UserSessionModel userSession) {
for (Map.Entry<String, String> attr : clientAuthAttributes.entrySet()) {
userSession.setNote(attr.getKey(), attr.getValue());
}
}
public Response buildResourceOwnerPasswordCredentialsGrant() {
event.detail(Details.AUTH_METHOD, "oauth_credentials");
if (!client.isDirectAccessGrantsEnabled()) {
event.error(Errors.NOT_ALLOWED);
throw new ErrorResponseException(OAuthErrorException.INVALID_GRANT, "Client not allowed for direct access grants", Response.Status.BAD_REQUEST);
}
if (client.isConsentRequired()) {
event.error(Errors.CONSENT_DENIED);
throw new ErrorResponseException(OAuthErrorException.INVALID_CLIENT, "Client requires user consent", Response.Status.BAD_REQUEST);
}
String scope = formParams.getFirst(OAuth2Constants.SCOPE);
AuthenticationSessionModel authSession = new AuthenticationSessionManager(session).createAuthenticationSession(realm, client, false);
authSession.setProtocol(OIDCLoginProtocol.LOGIN_PROTOCOL);
authSession.setAction(AuthenticatedClientSessionModel.Action.AUTHENTICATE.name());
authSession.setClientNote(OIDCLoginProtocol.ISSUER, Urls.realmIssuer(uriInfo.getBaseUri(), realm.getName()));
authSession.setClientNote(OIDCLoginProtocol.SCOPE_PARAM, scope);
AuthenticationFlowModel flow = realm.getDirectGrantFlow();
String flowId = flow.getId();
AuthenticationProcessor processor = new AuthenticationProcessor();
processor.setAuthenticationSession(authSession)
.setFlowId(flowId)
.setConnection(clientConnection)
.setEventBuilder(event)
.setRealm(realm)
.setSession(session)
.setUriInfo(uriInfo)
.setRequest(request);
Response challenge = processor.authenticateOnly();
if (challenge != null) return challenge;
processor.evaluateRequiredActionTriggers();
UserModel user = authSession.getAuthenticatedUser();
if (user.getRequiredActions() != null && user.getRequiredActions().size() > 0) {
event.error(Errors.RESOLVE_REQUIRED_ACTIONS);
throw new ErrorResponseException(OAuthErrorException.INVALID_GRANT, "Account is not fully set up", Response.Status.BAD_REQUEST);
}
AuthenticationManager.setRolesAndMappersInSession(authSession);
AuthenticatedClientSessionModel clientSession = processor.attachSession();
UserSessionModel userSession = processor.getUserSession();
updateUserSessionFromClientAuth(userSession);
AccessTokenResponse res = tokenManager.responseBuilder(realm, client, event, session, userSession, clientSession)
.generateAccessToken()
.generateRefreshToken()
.generateIDToken()
.build();
event.success();
return Cors.add(request, Response.ok(res, MediaType.APPLICATION_JSON_TYPE)).auth().allowedOrigins(uriInfo, client).allowedMethods("POST").exposedHeaders(Cors.ACCESS_CONTROL_ALLOW_METHODS).build();
}
public Response buildClientCredentialsGrant() {
if (client.isBearerOnly()) {
event.error(Errors.INVALID_CLIENT);
throw new ErrorResponseException(OAuthErrorException.UNAUTHORIZED_CLIENT, "Bearer-only client not allowed to retrieve service account", Response.Status.UNAUTHORIZED);
}
if (client.isPublicClient()) {
event.error(Errors.INVALID_CLIENT);
throw new ErrorResponseException(OAuthErrorException.UNAUTHORIZED_CLIENT, "Public client not allowed to retrieve service account", Response.Status.UNAUTHORIZED);
}
if (!client.isServiceAccountsEnabled()) {
event.error(Errors.INVALID_CLIENT);
throw new ErrorResponseException(OAuthErrorException.UNAUTHORIZED_CLIENT, "Client not enabled to retrieve service account", Response.Status.UNAUTHORIZED);
}
UserModel clientUser = session.users().getServiceAccount(client);
if (clientUser == null || client.getProtocolMapperByName(OIDCLoginProtocol.LOGIN_PROTOCOL, ServiceAccountConstants.CLIENT_ID_PROTOCOL_MAPPER) == null) {
// May need to handle bootstrap here as well
logger.debugf("Service account user for client '%s' not found or default protocol mapper for service account not found. Creating now", client.getClientId());
new ClientManager(new RealmManager(session)).enableServiceAccount(client);
clientUser = session.users().getServiceAccount(client);
}
String clientUsername = clientUser.getUsername();
event.detail(Details.USERNAME, clientUsername);
event.user(clientUser);
if (!clientUser.isEnabled()) {
event.error(Errors.USER_DISABLED);
throw new ErrorResponseException(OAuthErrorException.INVALID_REQUEST, "User '" + clientUsername + "' disabled", Response.Status.UNAUTHORIZED);
}
String scope = formParams.getFirst(OAuth2Constants.SCOPE);
AuthenticationSessionModel authSession = new AuthenticationSessionManager(session).createAuthenticationSession(realm, client, false);
authSession.setAuthenticatedUser(clientUser);
authSession.setProtocol(OIDCLoginProtocol.LOGIN_PROTOCOL);
authSession.setClientNote(OIDCLoginProtocol.ISSUER, Urls.realmIssuer(uriInfo.getBaseUri(), realm.getName()));
authSession.setClientNote(OIDCLoginProtocol.SCOPE_PARAM, scope);
UserSessionModel userSession = session.sessions().createUserSession(authSession.getId(), realm, clientUser, clientUsername, clientConnection.getRemoteAddr(), ServiceAccountConstants.CLIENT_AUTH, false, null, null);
event.session(userSession);
AuthenticationManager.setRolesAndMappersInSession(authSession);
AuthenticatedClientSessionModel clientSession = TokenManager.attachAuthenticationSession(session, userSession, authSession);
// Notes about client details
userSession.setNote(ServiceAccountConstants.CLIENT_ID, client.getClientId());
userSession.setNote(ServiceAccountConstants.CLIENT_HOST, clientConnection.getRemoteHost());
userSession.setNote(ServiceAccountConstants.CLIENT_ADDRESS, clientConnection.getRemoteAddr());
updateUserSessionFromClientAuth(userSession);
AccessTokenResponse res = tokenManager.responseBuilder(realm, client, event, session, userSession, clientSession)
.generateAccessToken()
.generateRefreshToken()
.generateIDToken()
.build();
event.success();
return Cors.add(request, Response.ok(res, MediaType.APPLICATION_JSON_TYPE)).auth().allowedOrigins(uriInfo, client).allowedMethods("POST").exposedHeaders(Cors.ACCESS_CONTROL_ALLOW_METHODS).build();
}
// https://tools.ietf.org/html/rfc7636#section-4.1
private boolean isValidPkceCodeVerifier(String codeVerifier) {
if (codeVerifier.length() < OIDCLoginProtocol.PKCE_CODE_VERIFIER_MIN_LENGTH) {
logger.infof(" Error: PKCE codeVerifier length under lower limit , codeVerifier = %s", codeVerifier);
return false;
}
if (codeVerifier.length() > OIDCLoginProtocol.PKCE_CODE_VERIFIER_MAX_LENGTH) {
logger.infof(" Error: PKCE codeVerifier length over upper limit , codeVerifier = %s", codeVerifier);
return false;
}
Matcher m = VALID_CODE_VERIFIER_PATTERN.matcher(codeVerifier);
return m.matches() ? true : false;
}
// https://tools.ietf.org/html/rfc7636#section-4.6
private String generateS256CodeChallenge(String codeVerifier) throws Exception {
MessageDigest md = MessageDigest.getInstance("SHA-256");
md.update(codeVerifier.getBytes());
StringBuilder sb = new StringBuilder();
for (byte b : md.digest()) {
String hex = String.format("%02x", b);
sb.append(hex);
}
String codeVerifierEncoded = Base64Url.encode(sb.toString().getBytes());
return codeVerifierEncoded;
}
}