It is not a kings chamber like you have learned from propaganda. The inner walls are made of marble, not sandstone and inside the pyramid is a perfect 68F degrees (20C)constantly. Some info why we know it is a perfect 68F (20C) inside:

Colonel Howard Vyse who, in 1837, at the expense of a large fortune, and after seven months of work, brought the Great Pyramid within the sphere of modern scientific investigation. Colonel Vyse re-opened the forced entry made originally by Al Mamoun early in the ninth century AD. He also rediscovered the corner-sockets previously uncovered by the French in 1799. When Vyse decided to clear away some debris by the pyramid, he discovered two of the original polished limestone casing stones. Vyse also discovered and opened up the air shafts to the King’s Chamber. He had discovered that these shafts extended over 200 feet to the outside of the pyramid. Once opened, an immediate rush of cool air entered the King's Chamber and maintained an even temperature of 68F degrees (20C) regardless of the weather outside.

The pyramid was used to manufacture drinkable water with the process of condensing sea water. With a pool of seawater inside the bottom of the pyramid, the inside relative humidity would be nearing 100%. We know the inside temp is 68F (explanation above) and the dew point is, you guessed it, the air is saturated and is at its dew point of 68F. If you do not understand condensation and dew points then look it up. There are several calculators on the net. If you do understand then you know the dew point is the temperature at which the water vapor in a sample of air at constant barometric pressure condenses into liquid water at the same rate at which it evaporates. Again, the dew point is the temperature at which the water vapor in a sample of air at constant barometric pressure condenses into liquid water at the same rate at which it evaporates thus leaving the salt behind in that process.
At temperatures below the dew point, water will leave the air. The condensed water is called dew when it forms on a solid surface like a marble wall. The marble walls collected the condensation and is now salt free palatable water.

How do I know this this process works inside the pyramid you ask?

In modern times the Pyramid of Khufu was closed on April 1, 1998 after it was discovered that the numbers of visitors had increased humidity inside the pyramid to 80%. We know that each visitor to the pyramids give out an average of about 20 grams of water through their breath and perspiration, which in turn ruins the plasters that cover part of the grand gallery by accumulating SALTS which leech into the plaster. The walls of the Grand Gallery of the pyramid were also found to be covered with up to 2cm of SALT. So we know this process works inside the pyramid, no conspiracy theory here.

So there you have it, the Giza pyramid explained. A pure drinking water machine for people living on the edge of a desert next to a salty sea.