to the card. It can then be combined with the nested authentication attack in the Nijmegen Oakland paper to recover subsequent keys almost instantly. Both attacks combined and with the right hardware equipment such as Proxmark3, one should be able to clone any MIFARE Classic card in 10 seconds or less. This is much faster than previously thought. In an attempt to counter these card-only attacks, new "hardened" cards have been released in and around 2011, such as the MIFARE Classic EV1. These variants are insusceptible for all card-only attacks publicly known until then, while remaining backward compatible with the original MIFARE Classic. In 2015, a new card-only attack was discovered that is also able to recover the secret keys from such hardened variants. Since the discovery of this attack, NXP is officially recommending to migrate from MIFARE Classic product-based systems to higher security products. MIFARE DESFire In November 2010, security researchers from the Ruhr University released a paper detailing a side-channel attack against MIFARE product-based cards. The paper demonstrated that MIFARE DESFire product-based cards could be easily emulated at a cost of approximately $25 in "off the shelf" hardware. The authors asserted that this side-channel attack allowed cards to be cloned in approximately 100 ms. Furthermore, the paper's authors included hardware schematics for their original cloning device, and have since made corresponding software, firmware and improved hardware schematics publicly available on GitHub. In October 2011 David Oswald and Christof Paar of Ruhr-University in Bochum, Germany, detailed how they were able to conduct a successful "side-channel" attack against the card using equipment that can be built for nearly $3,000. Called "Breaking MIFARE DESFire MF3ICD40: Power Analysis and Templates in the Real World", they stated that system integrators should be aware of the new security risks that arise from the presented attacks and can no longer rely on the mathematical security of the used 3DES cipher. Hence, to avoid, e.g. manipulation or cloning of smart cards used in payment or access control solutions, proper actions have to be taken: on the one hand, multi-level countermeasures in the back end allow to minimize the threat even if the underlying RFID platform is insecure," In a statement NXP said that the attack would be difficult to replicate and that they had already planned to discontinue the product at the end of 2011. NXP also stated "Also, the impact of a successful attack depends