Proxmark3 community

4814

Member

Registered: 2014-10-24

Posts: 3

How to tell if I am buying a magic card?

Hey,
I plan to clone my relatively big Mifare Classic card to a much smaller RFID-chip.
I looked for suiteable magic cards (sector 0 writeable) on tabao but I cant get from the description if the chip has this propertie.

Are they rewriteable if there is just the keyword UID in the title?
For example this item:
http://item.taobao.com/item.htm?spm=a230r.1.14.235.tjXJZD&id=39579601112&ns=1&abbucket=7#

Thanks for helping me out! I really don't want to buy the wrong chip as shipping is pretty expansible

iceman

Administrator

Registered: 2013-04-25

Posts: 9,538

Website

Re: How to tell if I am buying a magic card?

Plenty of people here can sell you a Mifare s50 or s70 with changeable uid

4814

Member

Registered: 2014-10-24

Posts: 3

Re: How to tell if I am buying a magic card?

Great!
However I want a small chip or a sticker to pin it on the back of my phone...

asper

Contributor

Registered: 2008-08-24

Posts: 1,409

Re: How to tell if I am buying a magic card?

If you want to use your phone you need to buy a version supported by the phone. Actually there are 2 "versions" of those changeable UID chips (probably manufactured by different people):

- 1 kind of tag (the oldest ones), also known as "backdoored", that means they need some special commands (backdoor) to be sent before you will be able to freely write any block; this one is NOT USABLE with ANY mobile phone
- a second kind of tag (newer) in which you can send normal mifare commands to freely write any bloc; this one can be used with mobile phones compatible with NFC and mifare (not all mobile phones support mifare).

It is IMPOSSIBLE to say which one are sold on internet, you need to ask the seller and even if it say you "yes, it is the newer one" you will not be able to know if this is the true until you test it.

If you do not have a proxmark3 or other specific hardware+software you will not be able to write the UID on the 1st kind of tags.

Last edited by asper (2014-10-24 20:26:11)

4814

Member

Registered: 2014-10-24

Posts: 3

Re: How to tell if I am buying a magic card?

Nah, I dont want to use it with mt phone. I plan to use a dedicated nfc reader/writer to clone my old card to a smaller chip...