Switching MIFARE Classic 1k Hotel Keycards

Today i am using the MIFARE Classic Tool app for android to demonstrate what happens when you use standard keys for hotel key cards. I am able clone and switch 2 cards for use on the same door. The keycards are using MIFARE Classic 1k RFID chips, and because they are write protected with known, standard keys, i am able to read and write to all 16 sectors of the key card, thus allowing me to clone, and/or switch them. Enjoy!