Hamming Quasi-Cyclic (HQC) has been selected by NIST for standardization in the post-quantum landscape. As deployment approaches, implementation security becomes as critical as mathematical hardness. In this work, we demonstrate that source-level constant-time coding is not a standalone guarantee: the compiled binary must inherently preserve this behavior. We identify a severe compiler-induced vulnerability within the official AVX2-optimized implementation of HQC, despite its claims of being constant-time. Although the C source code relies on secure, mask-based conditional selection, certain compiler optimizations rewrite this logic systematically. This transformation silently introduces secret-dependent control flow into the inner Reed-Muller decoding process, resulting in secret-dependent cache access patterns. Exploiting this vulnerability, we mount, to the best of our knowledge, the first cache-timing Full-Decryption-style oracle attack against a post-quantum cryptosystem. Using Flush+Reload on shared libraries, an unprivileged co-located adversary can extract fine-grained predicates of the decoder’s internal state. To achieve full key recovery, we develop a novel, reliability-aware Soft Information Set Decoding (Soft-ISD) post-processing framework. Leveraging a GPU-accelerated meet-in-the-middle strategy optimized for heterogeneous platforms (including Apple Silicon), we demonstrate end-to-end secret key recovery for hqc-1 with less than 10 s of online trace collection.

Since the synthetic aperture radar (SAR) images of internal wave contain additive and multiplicative noise under the ocean background, it is necessary to extract the internal wave to obtain the parameter information. This paper proposes a variational mode decomposition (VMD) method for separating and extracting internal waves. To solve the ambiguity in the estimation of direction, normalized radon transform in the elliptic domain is combined with the VDM, which can estimate the propagation direction of the internal waves accurately. Then performing experiments on Andaman Sea internal wave data collected by ERS-1 shows that VMD is least disturbed by the background information, and the estimation result of wavelength is closest to the measured value. At the same time, correct results are obtained by using the proposed method to estimate the propagation direction of the measured data from various sea areas, which proves the effectiveness of the proposed method.