Dear MIFARE Classic user,
This letter serves to inform you on the recent situation concerning the security deficiencies of our MIFARE Classic product.
By letters dated from February 2nd, March 13th; May 5th 2008 and July 11th we have informed you already on this subject.
NXP Semiconductors regrets to inform you on the decision of the court in Arnhem from July 18th to allow the publication by the IT security specialists from Radboud University Nijmegen, which includes attacks on MIFARE Classic systems. The University intends to present the publication during a conference on October 6th, with information on how the protocol and algorithm were reverse engineered, the description of the protocol and algorithm and the description of some practical attacks which can be carried out with limited means.
This report from the Radboud University Nijmegen will reduce the barrier to carry-out actual attacks on infrastructures using MIFARE Classic, which prompted our request for a delay in its publication in order to allow for reasonable time for appropriate system security upgrades. As we were not successful in our request, you may want to address your interests directly with the University of Nijmegen, in relation to the disclosure of security risks to your systems in the aforementioned publication.
By now, NXP Semiconductors has come to the conclusion that three research groups have retrieved the algorithm and developed attacks to break keys of MIFARE Classic-enabled cards within seconds. Besides the Radboud University Nijmegen, these are the group around Karsten Nohl, who initially presented the reverse engineering of MIFARE Classic chips in December 2007 at the 24th Chaos Computer Congress in Berlin and Nicolas T. Courtois from the University College London. Based on the aforementioned court decision we expect further publication of detailed findings around the security of MIFARE Classic by these research groups in the coming months.
Therefore, as we did before, we feel it is appropriate to inform you once more about the potential consequences and necessary measures to be taken to minimize the impact of possible attacks for your system infrastructure.
We are investigating protection scenarios for systems using MIFARE Classic, as in some systems insufficient mechanisms to detect fraudulent cards may have been implemented. Mindful of the above, we urgently ask you to contact your system integrator for an assessment of your systems. Extensive additional protection mechanisms are recommended, both on how the data on the card is used as well as deploying additional security layers separate from the card.
Naturally, your risk assessment depends on the assets to be protected and whether the end-to-end system still meets your requirements, which only you and your system integrator can determine.
End to end measures should also be applied for access management infrastructures, often by complementing systems with additional measures e.g. camera surveillance, security personnel, etc. when valuable assets need to be protected. We recommend that your assessment of the impact of the recent and expected developments takes into account the particular way how the system is implemented and used, its relation to other protection in place, and specifically whether there is a need to prevent unauthorized single time access or access during a limited period of time. Depending on the specific situation in existing MIFARE Classic access management infrastructures, in many cases the usage of more sophisticated card ICs may be recommendable. DESFire EV1 and MIFARE Plus (available in Q4 2008) are our recommended solution for new access management implementations where a strong level of security is required.
MIFARE Classic provides a benchmark in cost competitiveness, while the recently announced MIFARE Plus enables an optimal future-proof migration path when necessary. Both, MIFARE Plus and our new high-end product MIFARE DESFire EV1 offer strong AES encryption and are targeted to receive the internationally recognized Common Criteria certification.
NXP's expertise is the design and manufacturing of chips; although we do not design end to end security systems, we would be happy to continuously support your system integrator so that the best solutions are reached.
If you would have any questions, please contact us at . If, in addition, you would like to be kept informed about the developments in this matter, please send an email to as well. Additionally, we will be giving updates on the MIFARE website under http://mifare.net/security/mifare_classic.asp.
Sincerely yours
The NXP MIFARE team
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