The shell region of young supernova remnant (SNR) Cassiopeia A is a source of very energetic cosmic rays (CRs), but we do not know exactly, what are the candidate CRs responsible of the X-ray and very high energy gamma-ray emission and how these CRs are accelerated to such energies. To answer these questions, we have analyzed Chandra X-ray data from different parts of the shell of Cas A in the energy range of 0.7 - 8 keV. We have also analyzed gamma-ray data of Fermi-LAT, where we obtained a spectral index of 2.02 from the power-law fit to the GeV gamma-ray spectrum. We will present here the analysis results of X-ray and gamma-ray, as well as the multi-wavelength modeling of Cas A considering archival radio and TeV data along with Chandra and FermiLAT data.