Can Zhang Wen's laptop hard drive be cracked? BitLocker 48-bit key even makes supercomputers surrender.

North Taipei Random Killings Case: Suspect Zhang Wen Commits Suicide, Laptop Becomes Key Evidence

After the suspect Zhang Wen committed suicide, his rented apartment’s laptop became crucial for solving the case. Although the laptop was burned, the SSD drive was still operational but protected by Microsoft BitLocker encryption. Lawyers analyze that the 48-bit recovery key of BitLocker has a complexity equivalent to 2^128, making brute-force cracking require 60 billion years—even with quantum computers, it would still take 32 million years. The police have requested assistance from ASUS and Microsoft.

What is BitLocker? Standard Unlocking Methods Ineffective for Zhang Wen’s Laptop

(Source: Microsoft)

According to official Microsoft information, BitLocker is a built-in data protection feature in Windows operating systems, designed specifically to prevent data theft or leakage. Its operation encrypts the entire disk and works in conjunction with the Trusted Platform Module (TPM) in the hardware.

When BitLocker detects that the drive has been moved to another device or attempts to read data offline, the system automatically locks and prompts the user to enter a 48-bit “Recovery Key.” This design was originally intended to protect user confidential information if the computer is lost or stolen, ensuring that even if the hardware is stolen, internal files cannot be accessed without authorization. Zhang Wen’s laptop triggered this mechanism.

Why the Three Standard Methods of Unlocking BitLocker Are Ineffective for Zhang Wen’s Case

Microsoft Entra ID Cloud Backup: Requires logging into Zhang Wen’s Microsoft account and confirming that he backed up the key to the cloud, but police may not have access to the account or Zhang Wen may not have backed it up.

USB Recovery Drive: Requires finding a USB device containing the recovery password text file, but he may have never created or already destroyed it.

Enterprise Domain Administrator Assistance: Only applicable to company-issued computers; Zhang Wen’s personal gaming laptop does not qualify.

This also means that unless police can access Zhang Wen’s Microsoft cloud account, find the USB containing the key, or the laptop belongs to a corporate domain (highly unlikely), without that 48-bit recovery key, the drive is like a digitally welded safe—difficult to open.

Zhang Wen’s Analysis: The Mathematical Dead End of 60 Billion Years

(Source: Facebook)

How difficult is it to crack Zhang Wen’s laptop? Cybersecurity lawyer Xu Shiwei, a former prosecutor, provides a despairing mathematical analysis. The recovery key of BitLocker consists of 48 decimal digits, and its permutation complexity is slightly greater than 2^159. After accounting for checksum and structural constraints, the actual strength remains comparable to 2^128, an astronomical number.

Specifically, 2^128 is approximately 3.4 x 10^38. Even using the world’s fastest supercomputer, Frontier (performing 1.8 x 10^19 operations per second), it would take about 6 billion years to try all possible combinations. This timescale is about 43 times the current age of the universe. The Sun is expected to expand into a red giant and swallow the Earth in 5 billion years, but cracking Zhang Wen’s laptop would take 120 times that duration.

Can quantum computers be the savior? Xu Shiwei estimates that even with mature quantum computing technology in the future, the speed-up would only reduce the decryption time to the square root level, still requiring about 32 million years. Although this is much shorter than 6 billion years, it remains meaningless for criminal investigations.

Why the Police Still Attempt to Crack Despite Knowing the Impossibility

Given the extremely low probability of success, why does the Criminal Investigation Bureau still try? Xu Shiwei speculates that reasons include: police hope that manufacturers have hidden undisclosed backdoors, attempting to unlock via unofficial channels. This possibility exists, as cooperation (or confrontation) between law enforcement and tech companies has been a controversial topic worldwide.

Another reason is societal pressure and the urgency to solve the case. Zhang Wen’s random attacks at the North Taipei train station and Zhongshan South West commercial district caused widespread panic. The public is eager to understand his motives and whether accomplices are involved. The tablet has already been cracked by Taipei City Criminal Investigation Division, but police believe the laptop may contain more critical data, possibly revealing Zhang Wen’s motives.

Therefore, even with minimal chances of success, police must demonstrate their determination to exhaust all means. Currently, they have requested assistance from ASUS and Microsoft, and will also attempt brute-force cracking simultaneously. However, even with manufacturer help, success is uncertain and depends on how well Zhang Wen protected the drive.

This case also highlights the power and dilemma of modern encryption: it protects citizens’ privacy but can also serve as a perfect tool for criminals to hide evidence.