How to correctly use the authentication for nodeJs API using JWT and Passport ?

I am using JWT-simple for authenticating my express routes.

server side:

var jwt = require('jwt-simple');
var bcrypt = require('bcrypt');
var passport = require('passport');

require('../passport')(passport);

/* Create an Account */
router.post('/signup', function (req, res, next) {
    var verifyCode = Math.random().toString(36).slice(-8);
    var userData =  {
        name: req.body.name,
        email: req.body.email,
        phone: req.body.contact,
        password: req.body.password,
        verify_code: verifyCode,
        status: 0
    };

   loginService.createUser(userData, function (err, data) {
            if (err) {
                res.status(500).json({error: true, data: {message: err.message}});
            } else {
                var token = jwt.encode(data, "secret");
                res.json({success: true, data: {token: 'JWT ' + token}});
            }
        });
});
/* GET the info of an API using the jwt token data */
router.get('/info', passport.authenticate('jwt', {session: false}), function (req, res, next) {
    var token = tokenRetrive.getToken(req.headers);
    if (token) {
        var decoded = jwt.decode(token, configVar.config.secret);
        UserService.getContentUserById(decoded.id, function (err, user) {
            if (err) {
                res.status(500).json({error: true, data: {message: err.message}});
            } else {
                if (!user) {
                    res.send({success: false, msg: 'Authentication failed. User not found.'});
                } else {
                    if (!user) {
                        return res.status(403).send({success: false, msg: 'Authentication failed. User not found.'});
                    } else {
                        res.json({success: true, data: user.toJSON()});
                    }
                }
            }
        });
    } else {
        return res.status(403).send({success: false, msg: 'No token provided.'});
    }
});

client side

var signup = function(user) {
            return $q(function(resolve, reject) {
                $http.post(API_ENDPOINT.url + '/signup', user).then(function(result) {
                    if (result.data.success) {
                        storeUserCredentials(result.data.data.token);
                        resolve(result.data);
                    } else {
                        reject(result.data.msg);
                    }
                });
            });
        };

 function storeUserCredentials(token) {
            window.localStorage.setItem(TOKEN_KEY, token);
            var loggedIn_user_Data = jwt_decode(token);
            $http.defaults.headers.common.Authorization = token;
        }

Using REST client (POSTMAN) when I pass the header info to the API I use

API : localhost:8080/info

Key

Authorization
Content-Type   

Value

JWT eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJuYW1lIjoiYXR1bCIsImVtYWlsIjoidHJlZUB0cmVlLmNvbSIsInBob25lIjpudWxsLCJwYXNzd29yZCI6IiQyYSQxMCRIQVJPTy5PUEdYWFBvVktXOVhmYnZldkJRWldRaXNJa2JpT09WZHlsNmZxMlF2aURPOExBYSIsInZlcmlmeV9jb2RlIjoiMHdkZWlwYjkiLCJzdGF0dXMiOiIiLCJpZCI6MTYsImFkZHJlc3MiOm51bGwsImNvdW50cnkiOm51bGwsInN0YXRlIjpudWxsLCJwaW5jb2RlIjpudWxsLCJvcmdfaWQiOjAsInJvbGVzIjpudWxsLCJjcmVhdGVfZGF0ZSI6IjIwMTctMDUtMThUMTk6NTE6MDYuMDAwWiIsImxhc3RfbG9naW4iOiIyMDE3LTA1LTE4VDE5OjUxOjA2LjAwMFoiLCJhdmF0YXJfdXJsIjpudWxsfQ.umxBRd2sazaADSDOW0e8rO5mKDpQYIK1hsaQMZriZFE

application/json

The above API gives me the data only if the correct token is passed and seems working fine.

However in client side I can get the token retrieve using jwt-decode, without the use of any secret in client side, what if the token is caught by middle man, How can the security be enhanced?
Is there something I am missing to have correct use of JWT for my node api routes?

Some places I see the Authorisation is passed as bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJuYW1lIjoiYXR1bCIsImVtYWlsIjoidHJlZUB0cmVlLmNvbSIsInBob25lIjpudWxsLCJwYXNzd29yZCI6IiQyYSQxMCRIQVJPTy5PUEdYWFBvVktXOVhmYnZldk When I try to use bearer I get error to get the info after authenticating. What is this bearer and JWT being passed in value to header?

I am using passport-jwt var JwtStrategy = require('passport-jwt').Strategy;

via atjoshi