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Comment by privong | Hacker News Reader

I was able to read the RFID card at an Aloft hotel (they were mentioned in the article) using NFC on my phone. In principle, it should have been possible to clone that room card to my phone so I could have just used my phone, but I didn't pursue that.

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I always assumed hotel keycards are writable[1], so they just change the code on the card and associate the new one with the room whenever a new guest checks in. Knowing what the code was when you were staying there wouldn't be any help at all in the future.

[1] This sort of thing: http://proto-pic.co.uk/mifare-one-rfid-card-13-56mhz/?gclid=...

Some keycards are even completely disposable (paper / cardboard), though most of them are reprogrammable (plastic). I've seen hotel personnel swipe the card to grant me access to my room (with a new and/or unique key, etc.)

Definitely. I was more thinking about cloning the card so I could just use my phone to unlock the door instead, rather than trying to use it at some future date.

Often, the lock reads a time stamp from the keys and the lock only opens for fresh keys.

I had absolutely no idea my NFC reader on my Nexus could read my credit-card details, or other RFID stuff with NFC enabled -- rather scary!

To anyone who is interested, enable NFC on your 'droid, then on Google Play, download "Card Test" and voila...

I can see this (cloning a hotel key) being used in Person of interest.

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