Leaking secrets in homomorphic encryption with side-channel attacks
Leaking secrets in homomorphic encryption with side-channel attacks
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DOI：
10.1007/s13389-023-00340-2
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发表时间：
2024-01
影响因子：
1.9
通讯作者：
Furkan Aydin;Aydin Aysu
中科院分区：
文献类型：
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作者：
Furkan Aydin;Aydin Aysu
同态加密(HE)允许在不知道加密密钥的情况下在密文域中计算加密数据。然而，可以通过使用侧信道来破解完全同态加密(FHE)算法。本文演示了Microsoft SEAL HE库的侧通道泄漏。该攻击利用数论变换(NTT)算法中三进制值分配的泄漏，在密钥生成阶段窃取加密密钥。我们提出了两种攻击，一种是针对加减运算的-O0标志非优化代码实现，另一种是针对Guard和mul_root操作的-O3标志编译器优化。特别是，这些攻击可以从海豹突击队的NTT实现的单个功率/电磁测量痕迹中窃取密钥系数。为了实现单道跟踪的高精度，我们开发了新型的机器学习侧通道剖面器。在ARM Cortex-M4F处理器上，我们的攻击能够在禁用编译器优化时以98.3%的准确率提取密钥系数，在启用编译器优化时以98.6%的准确率提取密钥系数。最后，我们证明了我们的攻击可以避开随机延迟插入防御的应用。
Homomorphic encryption (HE) allows computing encrypted data in the ciphertext domain without knowing the encryption key. It is possible, however, to break fully homomorphic encryption (FHE) algorithms by using side channels. This article demonstrates side-channel leakages of the Microsoft SEAL HE library. The proposed attack can steal encryption keys during the key generation phase by abusing the leakage of ternary value assignments that occurs during the number theoretic transform (NTT) algorithm. We propose two attacks, one for-O0flag non-optimized code implementation which targetsadditionandsubtractionoperations, and one for-O3flag compiler optimization which targetsguardandmul_rootoperations. In particular, the attacks can steal the secret key coefficients from asinglepower/electromagnetic measurement trace of SEAL’s NTT implementation. To achieve high accuracy with asingle-trace, we develop novel machine-learning side-channel profilers. On an ARM Cortex-M4F processor, our attacks are able to extract secret key coefficients with an accuracy of 98.3% when compiler optimization is disabled, and 98.6% when compiler optimization is enabled. We finally demonstrate that our attack can evade an application of the random delay insertion defense.