Proxmark3 developers community

Research, development and trades concerning the powerful Proxmark3 device.

Remember; sharing is caring. Bring something back to the community.

"Learn the tools of the trade the hard way." +Fravia

You are not logged in.

#1 2019-02-22 19:36:34

Registered: 2019-02-20
Posts: 2

Multiple 125 KHz tags on a single card

I have embarked on a project to embed 125 KHz tags of different types on the same support. I have been doing a bit of research on the internet but the topic does not seem to have been treated much in depth.
To explain it better with an example: let's assume that I have an access controlled by a HID prox tag  reader and another controlled by a EM4100 reader, the objective is to use one and only one physical card/fob (call it, a "smart tag") to get it recognised by both the HID and the EM4100.
The constrains are that the "smart tag" be passive and of a cost comparable to a T5577.
Does anybody know of any solution already available (or a project underway) for this problem ?
One potential architecture is to have the smart tag send the various tags in sequence. Eeach reader would react when a tag of its own type is sent but not when the other types are. There are potentially many practical difficulties (time-outs, false positives, etc.) for such an implementation. Any better idea out there ?
Thanks in advance to everyone for any feedback.


#2 2019-02-22 19:43:11

Registered: 2013-04-25
Posts: 5,604

Re: Multiple 125 KHz tags on a single card

hm..  a card that can send out two different modulation schemas,  in a alternating way...   I don't think I ever seen a LF tag which can do that at the same time. T5577 can pretend different but only one at the time

If you feel the love,



#3 2019-08-12 01:05:02

Registered: 2019-08-11
Posts: 12

Re: Multiple 125 KHz tags on a single card

@am There is one solution I'm aware of. Not a card, but a FOB and pretty it would cover your needs. 4 cards on one. KEYSYS

My idea on it would be todo what COIN card and similar multi MAG cards with an interactive element do or did. It would be a more expensive project. R&D would be costly. The new thin film flexible lithium ceramic cells could be the ticket.

Couple that with the touch e-screen and or a couple thin film buttons to switch between them.

Another idea would be to use 4 of the cards or small form factor stickers. use an NO (normally open) thin film switch. Cut the antenna leads and solder them to the switch. place 4 on a card. Press and hold the one you want to be active.  --- That is just a dirty method. But a simple one.

Same method as mentioned in the dirty one. Remove 4 or 5 chips and use 1 card antenna. Connect leads to the chips and interrupt them again using the NO Thin film buttons. Would work....

Here is the KEYSYS though



Keysy supports 125kHz RFID keycards/keyfobs. These are typically perimeter access control systems that require the keycard/keyfob to be placed within 10cm of the reader. Anything that works farther away is unsupported.

Supported Models

HID Prox (Proxcard, ISOProx, ProxKey)
(Emulation not supported on multiClass readers, can still clone to rewritable)
HID Indala (Motorola Indala)
EM400x, EM410x, EM420x
Noralsy (KCP3000)
Farpointe Pyramid
Keri (KC-10X, MT-10X, PKT-10X)
Kantech ioProx
DoorKing (DKProx) [Not DKProx Long Range]
AWID (Low frequency only – CS-AWID, GR-AWID, KT-AWID, PW-AWID)
(Emulation not supported, can still clone to rewritable)
Radio Key (SecuraKey RKKT-01, RKKT-02)
Schlage IBF iButton (RFID portion only)
T55x7 compatible keycard/keyfob
Have a card/fob that isn’t on either list? Email with a picture of the card/fob and we will promptly take a look to determine if it is supported.

Unsupported Models

Automotive Keyfobs
Garage Door openers that require pushing a button (rather than waving in front of a reader)
Mass transit cards
Stored value cards
Hotel keys
HID iClass, iClass SE
Mifare Classic 1k/4k
Mifare Plus EV1
Mifare DESFire EV1/2
Mifare Ultralight
Farpointe Delta, Farpointe Ranger
DKProx Long Range (AVI)
AWID (all HF and UHF tags)
Any other RFID cards/fobs not operating at 125kHz.

yeah yeah


#4 2019-08-12 19:33:31

Registered: 2013-04-25
Posts: 5,604

Re: Multiple 125 KHz tags on a single card

the keysy is interesting but his design choice of locking down the t5577 card with his diversified key is just a dick move.

If you feel the love,



Board footer

Powered by FluxBB