What is the purpose of file signatures (magic numbers) in forensic analysis?

• A. To identify file types and validate data integrity when metadata is missing or corrupted
• B. To encrypt file contents
• C. To compress data
• D. To schedule automatic backups

Answer: (C)

File signatures, or magic numbers, identify a file’s type from its contents and help verify its structure when metadata is missing or corrupted. They’re fixed byte patterns at the start of many formats, allowing you to determine the true format even if the file extension is wrong or the header has been damaged. For example, a PNG begins with a specific eight-byte sequence, a PDF starts with “%PDF-”, and a ZIP file with the signature PK 03 04. In forensic work, this enables accurate classification, supports data carving from disk images, and helps spot mismatches between a file’s content and its stated type. These signatures are not encryption, compression, or scheduling mechanisms, and while they aid quick integrity checks, they don’t substitute for deeper integrity measures like hashes or digital signatures.