Help with authentication REST API

#1
private dispositivo = {
    "device_id" : "device",
    "device_os_version" : "5.0",
    "device_model" : "ASUS_T00J",
    "device_name" : "ZENFONE",
    "device_manufacturer" : "ASUS INC",
    
  };

constructor(
    public http: Http
  ) {
    
  }

  efetuarLogin(matricula:string, senha:string) {
    return new Promise((resolve, reject) => {
        let headers = new Headers();
        //headers.append("Authorization", "Basic" + btoa(login+ ":" + senha));
        headers.append("Authorization", "Basic XXXXXXXXXXXXXXXX");
        headers.append('Content-Type', 'application/json');
        
        console.log(headers);

        this.http.post(this.URL_API + '/login/loginapp', this.dispositivo, {headers: headers})
          .subscribe(res => {
            resolve(res.json());
            console.log(res)
          }, (err) => {
            reject(err);
            console.log(err);
          });
    });
  }