Chapter 249: The Night Before the Stress Test

The hard drive's read progress bar reached one hundred percent and gave a faint beep. One hundred thousand outpatient logs spread across the screen in CSV format, like a tract of wasteland that had never been cultivated. The fields were jumbled, timestamps followed different formats, and some sensitive columns even carried full-width spaces and invisible characters. Lin Chen did not frown. He pulled open a drawer, took out a cold can of instant coffee, poured it into a paper cup, and mixed in half a cup of warm water. Bitterness opened at the root of his tongue, dragging his nerves forcibly back into wakefulness.

"The penetration-test script has to be rewritten," he repeated, his fingers already landing on the keyboard.

Su Man did not ask why. She pulled over a chair and sat to one side, opened her own terminal, and began sorting through the hospital's desensitization-rule document. There was no unnecessary conversation between them, only the sound of keys and the occasional click of a mouse, cutting a taut rhythm through the office at four in the morning.

Lin Chen built the skeleton first. He abandoned the ready-made open-source desensitization libraries; their concurrency and memory management were too crude to withstand the brute-force scans of a third-party security firm. He created a new Python script, imported multiprocessing and asyncio, and split the data flow into separate read and write pipelines. The reader parsed the raw logs and cleaned dirty data; the processor invoked the SM4 national cryptographic algorithm for field-level encryption; the writer pushed the results into a temporary database. Every step was wrapped in strict exception handling and logging. He wrote slowly. After each function, he would run the boundary conditions through his head: How should null values be handled? Would overlong strings overflow? If concurrency suddenly spiked to five thousand, would memory burst?

The muscles in his left calf began to spasm again. He stopped typing, moved his foot down from the cardboard box, and set it on the cold floor tiles. Pain crawled upward along the Achilles tendon, like a blunt needle stirring between the bones. He took a deep breath, shifted all his weight onto his right leg, held the edge of the desk, and straightened himself, slowly rotating his ankle. The joint gave a faint click. He could not stop. Eight hours—after compilation and testing, less than six remained for coding. He sat back down, propped his left foot on the box again, and adjusted the code structure.

"There's a problem with the key-rotation logic for dynamic desensitization." Su Man's voice came from the side, soft but exact. "The hospital's unified authentication gateway refreshes its token every fifteen minutes. If our script is still encrypting with the old key during the stress test, they'll classify it directly as a data leak."

Lin Chen glanced at her screen. She had drawn a simple sequence diagram, marking the time gap between the gateway refresh and the script's encryption. It was indeed a blind spot. He brought up the code and added an asynchronous listener thread on the processing side, dedicated to catching the gateway's token-refresh event. The moment a new key arrived, it would switch encryption instances smoothly: old data streams would finish with the old key, while new streams connected seamlessly to the new one. No interruption, no packet loss. After writing that section, he saved and ran the local unit tests. Green PASS lines scrolled through the terminal. He rubbed his dry eyes and continued.

Time felt like a compressed spring, pushing forward little by little. At five in the morning, the reader pipeline ran through. At six, the encryption logic aligned. At seven, the concurrent stress simulation began. Lin Chen set the script's concurrency threshold to three thousand and imported ten thousand test records. The progress bar started jumping. CPU usage held steady at 65 percent; the memory curve climbed slowly, but garbage collection pushed it down before it reached the limit. No crash. No deadlock.

He leaned back in his chair and let out a long breath. The shirt on his back was already soaked through, clinging coldly to his skin.

"Run the full set," he said.

Su Man nodded and imported the one hundred thousand real logs. The progress bar started again. This time the data stream on the screen moved forward like a dark river, silently surging ahead. Lin Chen stared at the monitoring panel, his heartbeat rising and falling with the memory and CPU curves. Out of habit, he picked up a marker and wrote several key parameters on the whiteboard beside him: average response time 120 ms, peak memory usage 1.8 GB, error rate 0.01 percent. All were within the safety line.

But reality never ran according to script.

When the progress bar reached 87 percent, a red warning suddenly appeared on the monitoring panel: [WARNING] Field 'patient_id' collision detected. Hash conflict rate: 0.04%.

Lin Chen's pupils contracted slightly. A hash collision. Among one hundred thousand records, more than forty patients had generated the same anonymized ID. In medical data, that meant two different patients were being recognized by the system as the same person. If the stress test found it, the pilot qualification would be revoked outright.

"Stop." He immediately hit the interrupt key. The progress bar froze.

Su Man leaned in, her brows tightening. "Is it the SM4 block mode, or not enough salt?"

"The salt is fine." Lin Chen brought up the original collision data and compared it line by line. The problem lay in the hospital's legacy system. During early data entry, some patient ID numbers had been duplicated or formatted incorrectly, so the raw data already contained dirty points before cleaning. The script had merely encrypted that dirty data exactly as it was.

"We can't wait for the hospital to fix the source data." Lin Chen's voice was level, but his pace quickened. "We'll add a pre-validation layer before encryption. Run regular-expression cleaning on patient_id, strip out obviously invalid characters, then introduce the timestamp and a random number as a second salt to force the hash distribution apart. The collision rate has to be pushed below 0.001 percent."

"Pre-validation will add latency. The stress-test window is only two hours. If the delay exceeds 150 ms, the third party will mark the performance as substandard," Su Man pointed out.

"Performance can be optimized. A data-logic error is a red line." Lin Chen had already begun changing the code. He made the pre-validation module into an independent C extension, called through ctypes, bypassing Python's GIL to increase processing speed. His fingers flew over the keyboard, muscle memory overpowering fatigue. His left foot had gone completely numb, but he could no longer feel it. At that moment, his senses held only the characters on the screen, the fluctuation of memory, and the second hand of the countdown.

9:40 a.m. The modification was complete. The full data set was imported again.

The progress bar started once more. This time, the red warning did not appear. The curves on the monitoring panel were as steady as a straight line. Average response time: 135 ms, barely inside the safety line. Error rate: 0.0008 percent.

Lin Chen pressed save and closed the laptop. He leaned back in the chair and shut his eyes. Outside the window, the sky had begun to pale; gray-blue morning light passed through the glass, fell across the desktop, and illuminated scattered draft papers and empty coffee cans. The office was quiet, with only the low hum of the server fans.

"Package the script and generate the deployment document." He opened his eyes, his voice hoarse. "Send it to the information department before eleven. Have them deploy it to the test network segment in advance."

Su Man answered and began working. Her movements were crisp, without a wasted word. They had cooperated for too long; their tacit understanding had become instinct.

Lin Chen stood and walked to the window. When his left leg touched the floor, it suddenly softened, and he had to grip the windowsill to steady himself. A sharp stab came from his kneecap. He clenched his teeth and slowly straightened. The glass reflected his face: sunken eyes, messy stubble, but a very calm gaze.

His phone vibrated. It was a reply from Director Li of the hospital's information department: Script received. The third-party security company arrived early. They'll enter the site at 10:30. Get ready.

Lin Chen stared at the screen. Ten-thirty. An hour and a half earlier than planned.

He turned and looked at Su Man, who was organizing the documents. "They're entering early."

Su Man's hands paused for an instant, then resumed. "The document will be exported right away. I'll go to the server room and connect the cable."

"No need." Lin Chen returned to the desk, unplugged the portable hard drive, and slipped it into his jacket pocket. "A penetration test doesn't only look at scripts. It looks at on-site response. You stay in the office and watch the logs. I'll go to the server room."

He picked up his backpack and slid the laptop inside. The moment the strap tightened on his shoulder, the pain in his left foot became clear again. But he did not pause. He pulled open the door and stepped into the corridor.

The voice-activated lights in the hallway came on one by one with his footsteps. The light was stark white, falling on the fire-safety signs along the wall. Lin Chen walked slowly, but every step landed solidly. He knew the real test was not in the code, but in the hands of those people with scrutinizing eyes, scanning tools, and a finger ready at any moment to press the termination key.

The elevator doors opened. He stepped inside and pressed the button for Basement Level Two. The metal doors slowly closed, reflecting his calm profile.

The hard drive in his pocket pressed against his thigh, cold and heavy. Ten-thirty. The countdown had begun.