Exploitation of Cache Based Side-Channels on ARM

Abstract

Android smartphones collect and compile a huge amount of sensitive information which is secured using cryptography. There is an unintended leakage of information during the physical implementation of a cryptosystem on a device. Such a leakage is often termed as side channel and is used to break the implementation of cryptographic algorithms. In this work, we utilize cache memory based side channels on android smartphones to retrieve crypto-process information. These side channels are based on the information leakage through the operating system, micro-architecture of the processor and the state of the processor's memory cache. We demonstrate the retrieval of data dependent memory access patterns using a spy application running in the background to recover the full secret key of cryptographic primitives such as AES T-table implementation in OpenSSL, all that would be necessary is a rogue app downloaded from an app store that is run under normal privileges.
We show that a mathematical correlation which depends on the guessed key and can be utilized to recover the \emph{complete} key in access-driven cache attacks (CAs). We show the effectiveness of the proposed method using access time measured in noisy environments. We analyze the changes in the correlation values with the number of plaintexts/ciphertexts for a successful attack using key estimation. Furthermore, we discuss and demonstrate the applicability of cache memory based side channel attacks on a white-box implementation of AES.