Defeating ISO9797-1 MAC Algo 3 by Combining Side-Channel and Brute Force Techniques

Side-channel analysis is a well-known and efficient hardware technique to recover embedded secrets in microprocessors. Over the past years, the state-of-the-art side-channel attacks has significantly increased, leading to a myriad of vulnerability paths that secure codes must withstand. Nowadays most of the attacks target the cryptographic algorithms, but very few exploit the cryptographic protocol. In this paper, we present a new attack that exploits the information exchange at the cryptographic protocol level in order to disclose the secret key. This attack is applicable to the MAC calculations standardized in ISO/IEC 9797-1 especially the MAC algorithm 3 with the DES function. This protocol is spread in secure products nowadays, this is the case typically for some EMV implementations. By using a side-channel technique combined with a reasonable brute force effort, we show that the secret key can be fully retrieved even though the DES implementation seems to be well-protected against side-channel attacks

Comparative Study of Various Approximations to the Covariance Matrix in Template Attacks

Template attacks have been shown to be among the strongest attacks when it comes to side–channel attacks. An essential ingredient there is to calculate the inverse of a covariance matrix. In this paper we make a comparative study of the effectiveness of some 24 different variants of template attacks based on different approximations of this covariance matrix. As an example, we have chosen a recent smart card where the plain text, cipher text, as well as the key leak strongly. Some of the more commonly chosen approximations to the covariance matrix turn out to be not very effective, whilst others are

Cryptanalysis of GlobalPlatform Secure Channel Protocols

GlobalPlatform (GP) card specifications are the de facto standards for the industry of smart cards. Being highly sensitive, GP specifications were defined regarding stringent security requirements. In this paper, we analyze the cryptographic core of these requirements; i.e. the family of Secure Channel Protocols (SCP). Our main results are twofold. First, we demonstrate a theoretical attack against SCP02, which is the most popular protocol in the SCP family. We discuss the scope of our attack by presenting an actual scenario in which a malicious entity can exploit it in order to recover encrypted messages. Second, we investigate the security of SCP03 that was introduced as an amendment in 2009. We find that it provably satisfies strong notions of security. Of particular interest, we prove that SCP03 withstands algorithm substitution attacks (ASAs) defined by Bellare et al. that may lead to secret mass surveillance. Our findings highlight the great value of the paradigm of provable security for standards and certification, since unlike extensive evaluation, it formally guarantees the absence of security flaws