Abstract. Replay attacks are often the most costly attacks to thwart when dealing with off-chip memory integrity. With a trusted System-on-Chip, the existing countermeasures against replay require a large amount of on-chip memory to provide tamper-proof storage for metadata such as hash values or nonces. Tree-based strategies can be deployed to reduce this unacceptable overhead; for example, the well-known Merkle tree technique decreases this overhead to a single hash value. However, it comes at the cost of performancekilling characteristics for embedded systems -e.g. non-parallelizable hash computations on tree updates. In this paper, we propose an alternative solution: the Tamper-Evident Counter Tree (TEC-Tree). It allows for tamper-evident offchip storage of the nonces involved in a replay countermeasure; TEC-Tree parallelizes the computations involved in both the authentication and tree update processes. Moreover, because our tree relies on block encryption, it provides data confidentiality at no extra cost. TEC-Tree is a deployable solution for memory integrity, with low performance hit and hardware cost.

This paper describes a novel engine, called PE-ICE (Parallelized Encryption and Integrity Checking Engine), enabling to guarantee confidentiality and integrity of data exchanged between a SoC (System on Chip) and its external memory. The PE-ICE approach is based on an existing block-encryption algorithm to which the integrity checking capability is added. Simulation results show that the performance overhead of PE-ICE remains low (below 4%) compared to block-encryption-only systems (which provide data confidentiality only).

Abstract

This paper describes a novel engine, called PE-ICE (Parallelized Encryption and Integrity Checking Engine), enabling to guarantee the confidentiality and the integrity of data exchanged between a SoC (System on Chip) and its external memory by adding the integrity checking capability to a block encryption algorithm.

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