On Leakage-Resilient Authenticated Encryption with Decryption Leakages

Abstract

At CCS 2015, Pereira et al. introduced a pragmatic model enabling the study of leakage-resilient symmetric cryptographic primitives based on the minimal use of a leak-free component. This model was recently used to prove the good integrity and confidentiality properties of an authenticated encryption scheme called DTE when the adversary is only given encryption leakages. In this paper, we extend this work by analyzing the case where decryption leakages are also available. We first exhibit attacks exploiting such leakages against the integrity of DTE (and variants) and show how to mitigate them. We then consider message confidentiality in a context where an adversary can observe decryption leakages but not the corresponding messages. The latter is motivated by applications such as secure bootloading and bitstream decryption. We finally formalize the confidentiality requirements that can be achieved in this case and propose a new construction satisfying them, while providing integrity properties with leakage that are as good as those of DTE.

Secure Video Surveillance Framework in Smart City

“…(2) Cloud-based video surveillance saves a lot of storage resources and provides a convenient and low-cost monitoring capability for small-scale scene applications such shops and families. However, shops and families often lack security awareness and protection skills, which makes web cameras and monitors (most of the time, the monitor is just a normal personal computer) vulnerable [ 33 , 34 ].…”

Improved Leakage-Resistant Authenticated Encryption based on Hardware AES Coprocessors

“…In [BBC + 20], the authors present a practical side-channel attack against a tag verification implemented on an ARM Cortex-M0. It can directly be used to forge valid messages under adversarial control [BPPS17], and therefore to break the integrity of a software update. We repeat that experiment with two differences: (i) we use an ARM Cortex-M4 which is more noisy, and (ii) we do template attacks in a linear subspace instead of directly in the leakage domain.…”

“…While this appears as a strong motivation given the challenge of implementing masking securely on low-end devices [BS20], we observe that the main security property that is required for this purpose is ciphertext integrity with leakage in decryption. As discussed in [BPPS17], this property can be reached with two calls to a strongly protected block cipher and letting most of the other parts of the implementation leak in an unbounded manner. Yet, it requires a careful instantiation of the tag verification.…”

“…Namely, either this tag verification is protected at the implementation level (e.g., via masking), which contradicts the goal of relying only on hardware coprocessors, or it has to be designed such that leaking the verified value cannot lead to forgeries. It is shown in [BPPS17] that an inverse-based verification can remain secure with unbounded leakages. The variant in [DEM + 20] achieves a similar result without inverse, but based on a slightly stronger assumption, which translates into security against Simple Power Analysis (SPA).…”

“…We finally mention that the issue of secure tag comparison is not a new one in cryptography. It has been frequently discussed in the context of authenticated encryption and has for example been put forward by both Barwell et al [BPS15] and Berti et al [BPPS17].…”