<![CDATA[Perangkat wearable mengirimkan data detak jantung melalui kanal nirkabel yang tidak menyediakan jaminan bahwa nilai yang diterima sama dengan nilai yang dikirim. Perlindungan kriptografis konvensional sulit diterapkan pada gateway bersumber daya terbatas. Skema fragile watermarking juga tidak sesuai karena menolak setiap perubahan, termasuk kompresi yang sebenarnya tidak berbahaya. Penelitian ini mengimplementasikan mekanisme semi-fragile watermarking pada gateway tertanam untuk memverifikasi integritas data detak jantung. Setiap blok berisi 16 sampel data detak jantung yang didekomposisi menggunakan transformasi wavelet Haar tingkat satu. Watermark dibangkitkan dari koefisien aproksimasi melalui fungsi hash kriptografis, lalu disisipkan ke koefisien detail melalui modulasi indeks kuantisasi. Sistem divalidasi secara menyeluruh menggunakan smartwatch komersial berbasis sensor fotopletismografi (PPG) dengan antarmuka BLE yang diuji pada 8 subjek dalam 16 sesi. Sebanyak 247 blok yang terkumpul dievaluasi melalui 16 skenario ketahanan. Ekstraksi watermark berlangsung tanpa kesalahan pada kondisi transmisi normal. Kualitas sinyal rata-rata mencapai 41,59 desibel, akurasi deteksi manipulasi mencapai 96,1 persen, dan waktu komputasi rata-rata 87,16 milidetik per blok. Hasil tersebut menegaskan bahwa verifikasi integritas yang ringan layak dijalankan pada gateway tertanam berbiaya rendah tanpa perangkat keras kriptografis khusus. ABSTRACT Wearable devices transmit heart rate data across wireless channels that offer no inherent guarantee that the values received match those that were sent. Conventional cryptographic protection is hard to deploy on resource-constrained gateway hardware. Fragile protection is unsuitable as well, because it rejects every modification, including harmless compression. This study implements a semi-fragile watermarking mechanism on an embedded gateway to verify heart rate data integrity. Each block of 16 samples of heart rate data is decomposed by a first-level Haar wavelet transform. A watermark is then derived from the approximation coefficients through a cryptographic hash function and embedded into the detail coefficients by quantization index modulation. The system was validated end to end on a commercial smartwatch with a photoplethysmography (PPG) sensor over BLE test by 8 subjects across 16 sessions. The resulting 247 blocks were evaluated under 16 robustness scenarios. Watermark extraction was error free under normal transmission. Average signal quality reached 41.59 decibels, tamper detection accuracy reached 96.1 percent, and computation averaged 87.16 milliseconds per block. These results confirm that lightweight integrity verification is feasible on low-cost embedded gateways without dedicated cryptographic hardware.]]>
