n Wolf Pak Capturen What Is SHA-256?
SHA-256 (Secure Hash Algorithm 256-bit) is a cryptographic function that takes any file — a document, image, web page, or archive — and produces a unique 64-character “fingerprint” called a hash.
This hash has several critical properties:
- Deterministic: The same file always produces the same hash
- Unique: Even a single-bit change in the file produces a completely different hash
- One-way: You cannot reconstruct the original file from its hash
- Fixed-length: Every hash is exactly 64 characters, regardless of file size
Example: the SHA-256 hash of “Hello, World!” is:
dffd6021bb2bd5b0af676290809ec3a53191dd81c7f70a4b28688a362182986f
Change even one character — “Hello, World” (no exclamation mark) — and the hash changes completely:
03675ac53ff9cd1535ccc7dfcdfa2c458c5218371f418dc136f2d19ac1fbe8a5
Why SHA-256 Matters for Evidence
In digital evidence, the fundamental challenge is proving that a file hasn’t been altered. Unlike physical evidence (which shows visible signs of tampering), digital files can be modified without any visible indication.
SHA-256 hashing solves this by creating a tamper-detection mechanism:
- At the time of capture, hash each evidence file
- Record all hashes in a manifest
- At any later point, re-hash the files
- If any hash doesn’t match, the file has been modified
This process is deterministic and verifiable by anyone — no special tools, no proprietary systems, no vendor dependency.
How AEGIS Uses SHA-256
AEGIS generates a SHA-256 hash for every file in the evidence package and compiles them into a SHA256_MANIFEST.sha256 file. This manifest includes:
| File | SHA-256 Hash |
|---|---|
| SCREENSHOT_FULL.png | a3b0c44298fc1c149... |
| FORENSIC_ARCHIVE.mhtml | a7ffc6f8bf1ed7651... |
| PAGE_SOURCE.html | 2c26b46b68ffc68ff... |
| EXTRACTED_TEXT.txt | fcde2b2edba56bf40... |
| … (all 10 files) | ... |
The manifest is then digitally signed using RSA-2048 encryption, creating an additional layer of tamper detection. If anyone modifies a file, the hash won’t match. If anyone modifies the manifest, the digital signature won’t verify.
Verifying SHA-256 Hashes
One of SHA-256’s strengths is that anyone can verify the hashes using free, widely available tools:
- Windows:
certutil -hashfile filename SHA256 - macOS/Linux:
sha256sum filename - Online tools: Multiple free SHA-256 calculators exist
No proprietary software is needed. No vendor account is required. The verification is entirely independent.
The Bottom Line
SHA-256 hashing is the industry standard for proving file integrity. When combined with digital signatures and blockchain timestamping, it creates a multi-layered verification system that makes evidence tampering mathematically detectable.
AEGIS hashes every evidence file automatically — no manual steps, no extra tools needed.