Abstract.The mifare Classic is a contactless smart card that is used extensively in access control for office buildings, payment systems for public transport, and other applications. We reverse engineered the security mechanisms of this chip: the authentication protocol, the symmetric cipher, and the initialization mechanism. We describe several security vulnerabilities in these mechanisms and exploit these vulnerabilities with two attacks; both are capable of retrieving the secret key from a genuine reader. The most serious one recovers the secret key from just one or two authentication attempts with a genuine reader in less than a second on ordinary hardware and without any pre-computation. Using the same methods, an attacker can also eavesdrop the communication between a tag and a reader, and decrypt the whole trace, even if it involves multiple authentications. This enables an attacker to clone a card or to restore a real card to a previous state.

IMSI catching is a problem on all generations of mobile telecommunication networks, i.e., 2G (GSM, GPRS), 3G (HDSPA, EDGE, UMTS) and 4G (LTE, LTE+). Currently, the SIM card of a mobile phone has to reveal its identity over an insecure plaintext transmission, before encryption is enabled. This identifier (the IMSI) can be intercepted by adversaries that mount a passive or active attack. Such identity exposure attacks are commonly referred to as 'IMSI catching'. Since the IMSI is uniquely identifying, unauthorized exposure can lead to various location privacy attacks. We propose a solution, which essentially replaces the IMSIs with changing pseudonyms that are only identifiable by the home network of the SIM's own network provider. Consequently, these pseudonyms are unlinkable by intermediate network providers and malicious adversaries, and therefore mitigate both passive and active attacks, which we also formally verified using ProVerif. Our solution is compatible with the current specifications of the mobile standards and therefore requires no change in the infrastructure or any of the already massively deployed network equipment. The proposed method only requires limited changes to the SIM and the authentication server, both of which are under control of the user's network provider. Therefore, any individual (virtual) provider that distributes SIM cards and controls its own authentication server can deploy a more privacy friendly mobile network that is resilient against IMSI catching attacks.

The Mifare Classic is the most widely used contactless smartcard on the market. The stream cipher CRYPTO1 used by the Classic has recently been reverse engineered and serious attacks have been proposed. The most serious of them retrieves a secret key in under a second. In order to clone a card, previously proposed attacks require that the adversary either has access to an eavesdropped communication session or executes a message-by-message man-in-the-middle attack between the victim and a legitimate reader. Although this is already disastrous from a cryptographic point of view, system integrators maintain that these attacks cannot be performed undetected. This paper proposes four attacks that can be executed by an adversary having only wireless access to just a card (and not to a legitimate reader). The most serious of them recovers a secret key in less than a second on ordinary hardware. Besides the cryptographic weaknesses, we exploit other weaknesses in the protocol stack. A vulnerability in the computation of parity bits allows an adversary to establish a side channel. Another vulnerability regarding nested authentications provides enough plaintext for a speedy known-plaintext attack.

Near Field Communication (NFC) technology enables devices to communicate wirelessly within proximity distance. These NFC devices are often embedded into smart posters that offer the ability to exchange small files, photos and contact details. The Nokia 6212 Classic is currently the most popular NFC phone. It allows users to easily exchange digital objects using the NFC interface. To do so, two phones should be within the proximity coupling distance of 5 cm. This paper shows that the NFC feature that invokes a Bluetooth connection without user consent can be abused to surreptitiously install malicious software on the phone. This results in a serious vulnerability when smart posters start installing malicious software or spreading viruses.

Atmel CryptoMemory devices offer non-volatile memory with access control and authenticated encryption. They are used in commercial and military applications e.g. to prevent counterfeiting, to store secrets such as biometric data and cryptographic keys, and in electronic payment systems. Atmel advertises the devices as "secure against all the most sophisticated attacks, [...] including physical attacks". We developed a successful power analysis attack on the authentication step of CryptoMemory devices. Despite the physical security claims by Atmel we found that the devices are not protected against power analysis attacks, except for counters that limit the number of (failed) authentication attempts, and thus power traces, to at most three. We examined the handling of these counters and discovered a flaw that allows us to bypass them, and to obtain power traces from an unlimited number of failed authentication attempts. Our attacks need as few as 100 power traces to recover the secret 64-bit authentication keys. From measurements to full key extraction, the attacks can be carried out in less than 20 minutes on a standard laptop. Once the keys are known, an adversary can read protected contents, clone devices, and manipulate the memory at will, e.g. to set the balance of an electronic wallet. To our knowledge, this is the first power analysis attack on Atmel CryptoMemory products reported in the literature.