I am working on a project, where I am using RFID tags, and RFID reader for some sort of authentications.

But after searching for a while, I found that passive RFID tags can be cloned. Is there any way to make copy proof? (As far I know it is not possible.)

What logic should I use that won't allow duplicate card to not get access? (By using software or hardware logic.)

What is the latest happening in RFID and NFC technologies?


Yes, it is quite possible to make passive tags secure, but the tag must have some local processing power, not just a static read-only memory that it reads out.

The general algorithm is called "challenge-response". The reader and the tag share some secret piece of data, but this data is never transmitted over the air. Instead, the reader chooses some random data, sends this to the tag, which performs a cryptographically-secure transformation on the data that depends on the secret data, and then sends the transformed data back to the reader. Internally, the reader performs the same transformation, and if the two results match, then the tag is known to be valid.

Such a tag cannot be cloned simply by eavesdropping on the radio signal. Of course, if an attacker physically opens the tag and reads out the secret data (along with the transformation algorithm), all bets are off.

  • \$\begingroup\$ "...but the tag must have some local processing power..." How will this be possible in complete passive tags ?..are you talking about Semi Passive tags? \$\endgroup\$ – Vish Mar 21 '14 at 15:05
  • \$\begingroup\$ The processor is powered by the radio signal for the entire duration of the challenge-response cycle. It can be a bit of a challenge to pick an algorithm that provides adequate security while requiring a minimum of energy (power * time) to compute. \$\endgroup\$ – Dave Tweed Mar 21 '14 at 15:08
  • \$\begingroup\$ Ohk....so where can i find such tags? Do they have specific name? \$\endgroup\$ – Vish Mar 21 '14 at 15:13
  • \$\begingroup\$ I've read somewhere (but am too lazy to find now) that this scheme has some weaknesses. Think about it: by nature of how these things work, you must hand control of the power supply over to an attacker. By doing bad things to the power supply, an attacker can make the device operate in bad ways which disclose information about the key, eventually allowing it to be recovered. \$\endgroup\$ – Phil Frost Mar 21 '14 at 19:37
  • 3
    \$\begingroup\$ Which just emphasizes the point that there is no such thing as absolute security. The best you can do is to make the cost of breaking the security comparable to the value of what is being secured, removing the economic incentive. \$\endgroup\$ – Dave Tweed Mar 21 '14 at 19:53

Some years ago, when I had to implement a Mifare Classic system, I ask myself the same question and stumbled over this document: Making the Best of Mifare Classic from Radboud University Nijmegen October 6, 2008.
I don't know if you plan on using Mifare Classic, but it is a good read (but somewhat academic) and provides some interesting insight that might also apply to other RFID types.

It discusses a lot of known and potential vulnerabilities and proposes different types of countermeasures. The two main classes of attacks are discussed, which are "cloning" and "state restoration". As part of the countermeasures, it introduces a solid mechanism against "tearing" (data corruption due to the card being teared out of the field before all data has been written to a block).

"The Mifare Classic has a number of security features built in. Some turned out to be flawed. Some features, which are not particularly advertised as security features, can be used as a building block for additional security mechanisms. This document describes such additional security mechanisms.
As a result, it is possible to prevent successful state restoration attacks, and to prevent cloning attacks. That is, we currently believe these countermeasures are eective. However, they are provided "as is". We welcome feedback, decent peer review and further research is required. Crucially, though obviously, our countermeasures will not be eective if the features which are used as building blocks work can be circumvented. New attacks might appear which could make the countermeasures described in this document obsolete. Of course, similar reasoning applies to any kind of RFID card."


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