RFID hacking

1st question- How to read the data that is stored in a non-changeable tag? I mean not only the UID but also the 16 bits or bytes (not sure) of something written. Note: I only have to READ, not WRITE over it.

2nd question- After I've successfully completed #1 step, how to write the "something written" to the new tag (this should result in cloning the secret data of "something" :D) ?

3rd question- Actually, how do the locks-with-tags on storey buildings work? Do they read the UID or the secret data?

Thank you!

1st question- How to read the data that is stored in a non-changeable tag? I mean not only the UID but also the 16 bits or bytes (not sure) of something written.

Depends on the hardware used.

Note: I only have to READ, not WRITE over it.

That's clear as you specified a non-changeable tag.

2nd question- After I've successfully completed #1 step, how to write the "something written" to the new tag (this should result in cloning the secret data of "something" :D) ?

That's not possible as your specification says "non-changeable tag".

3rd question- Actually, how do the locks-with-tags on storey buildings work? Do they read the UID or the secret data?

Depends on the hardware used.

Lol, nice answers. Well, by using the "Read and Write" basic sketch I could write my own info but not change the UID. What I meant by saying "unchangeable" is that the UID cant be modified but the info on the card CAN. And what do you mean with "Depends on the hardware used."? I am using MFRC522 and Arduino Uno R3. Again thanks.

And what do you mean with "Depends on the hardware used."?

There are about half a dozen standards about RFID and 13.56MHz RFID tags are complete different from the 125kHz types. You should provide as much information about your setup as possible! We cannot see it (as you can) so we depend on the information you provide.

In the "locks-with-tags" section there are a lot of manufacturers. Not all use the same techniques to make their lock safe, many even don't tell you (they probably think security by obscurity still works today). At least some of the manufacturers don't use RFID standards but some proprietary protocols, as far as I know some even have more than just storage on their key tags.

I am using MFRC522 and Arduino Uno R3.

And what type of tags are you using? MIFARE (which type) or NTAG? I don't want to guess again.

Its MIFARE 1KB