This scenario aligns with CHFI v11 objectives under Anti-Forensics Techniques, specifically techniques used by attackers to prevent investigators from accessing digital evidence. Data encryption is a well-known and widely used anti-forensic method where files are encrypted using strong cryptographic algorithms and protected with complex passwords. While encryption is a legitimate security control, adversaries often misuse it to deliberately obstruct forensic analysis and delay investigations.

CHFI v11 explains that encrypted files render data unreadable without the correct decryption key, making it extremely difficult for investigators to examine file contents within acceptable timeframes. This can significantly hinder evidence discovery, timeline reconstruction, and incident scoping. Investigators must then rely on password cracking, key recovery, memory forensics, or legal assistance to access the data---each of which introduces complexity, cost, and time delays.

Data manipulation involves altering or deleting evidence, data obfuscation focuses on making data confusing but still accessible, and data hiding conceals information in alternate locations. In contrast, the defining characteristic in this scenario is password-protected encrypted files, which directly corresponds to data encryption. Therefore, consistent with CHFI v11 classifications, data encryption is the correct anti-forensic technique being employed.