Timing Side-Channel Measurements of Early-Exit and Fixed-Work Comparisons on ESP32 and ESP8266

This dataset contains 40,800 raw CPU-cycle measurements from an experimental characterization of early-exit and fixed-work secret-comparison routines on ESP32 and ESP8266 microcontrollers. For each device, measurements were collected under interrupt-protected and unprotected conditions. The four CSV files each contain 10,200 observations: 300 repetitions for every prefix-match length from 0 to 16, for both an early-exit comparison (mode V) and a fixed-work XOR/OR comparison (mode C). Each CSV records trial_id, mode, prefix_match_len, match_result, and cpu_cycles. No raw observations were removed or filtered. The measurements use on-device CPU cycle counters; the fixed-work source implementation is not a formal constant-time security guarantee, and the dataset alone does not demonstrate a practical secret-recovery attack. Acquisition order and additional limitations are documented in the included README. The Arduino and Python source code and unpublished manuscript are not included in this dataset. Associated GitHub data repository: https://github.com/Abrarcancode67/esp32-esp8266-timing-sidechannel-data. Creator: Abrar Sobhan. License: Creative Commons Attribution 4.0 International (CC BY 4.0).