code: public static boolean isArrayByteBase64(byte[] arrayOctet) {
          for (int i = 0; i < arrayOctet.length; i++) {
              if (!isBase64(arrayOctet[i]) && !isWhiteSpace(arrayOctet[i])) {
                  return false;
              }
          }
          return true;
      }
docs: Tests a given byte array to see if it contains only valid characters within the Base64 alphabet. Currently the
  method treats whitespace as valid.
  
  @param arrayOctet
  byte array to test
  @return <code>true</code> if all bytes are valid characters in the Base64 alphabet or if the byte array is empty;
  false, otherwise