How CaseStamp Works

Last updated: July 19, 2026

CaseStamp doesn't invent its own security or location methods. Every technical element is built on published, internationally recognized standards, computed by the device's own certified system libraries. This page documents what each one is and where it comes from, so a skeptical user, a lawyer, or any other professional can verify the app's methods rest on recognized standards, not proprietary claims.

File integrity — SHA-256

What it does: produces a unique 64-character fingerprint of each photo or video the moment it's saved. If even one byte of the file is later altered, the fingerprint changes completely, so any tampering is detectable.

Standard: SHA-256 is part of the SHA-2 family, published by the U.S. National Institute of Standards and Technology (NIST) in federal standard FIPS 180-4. It is a public standard, used worldwide in banking, government, and security.

How CaseStamp uses it: the hash is computed on-device by the operating system's built-in cryptographic library (Web Crypto API). CaseStamp does not implement its own cryptography.

On iOS, the current version displays a shortened hash in the exported PDF; the full 64-character hash display ships in the next iOS update. Android PDFs show the full 64-character hash today.

Location — GPS / WGS 84

What it does: tags each entry with the coordinates where it was captured, plus an accuracy value (e.g. ±5m) showing how precise the fix was.

Standard: coordinates come from the Global Positioning System (GPS) and are expressed in the WGS 84 world reference datum. CaseStamp requests a fresh location fix at the moment of capture — not a cached or previous location.

Offline: GPS is satellite-based and works without a network connection, though a fix may take longer offline. If no location can be obtained, the entry still saves and is marked "location unavailable" — CaseStamp never substitutes an old or approximate location.

How CaseStamp uses it: location comes from the device's native location services; CaseStamp reads the result, it does not estimate position itself.

Time — ISO 8601

What it does: stamps each entry with the date and time it was saved. The timestamp is set at save time and is never editable anywhere in the app.

Standard: timestamps follow ISO 8601, the international standard for representing dates and times.

The report — PDF

What it does: exports a case as a form-style chain-of-custody document.

Standard: PDF is an open international standard (ISO 32000), readable on virtually any device.

Verifying a report

Because these are open, published standards implemented by the device's own certified libraries, anyone receiving a CaseStamp report can independently verify a file against its printed SHA-256 hash using any standard tool.

To verify a file yourself:

On Mac or Linux: open Terminal and run shasum -a 256 filename
On Windows: open Command Prompt and run certutil -hashfile filename SHA256

If the file is unaltered, the result will exactly match the SHA-256 hash printed in the report for that entry. If even one byte has changed, the hashes won't match.

Example (placeholder data, not a real case):

Suppose a report lists this hash for a video —

c54bae9222ab83f222442b8ceec82ed35985f2be14bb5ce411601f425d7b2a32

You run:

shasum -a 256 entry-004.mp4

and get back:

c54bae9222ab83f222442b8ceec82ed35985f2be14bb5ce411601f425d7b2a32

The two strings match exactly, so the file is unaltered. If even one character differed, the file would have been changed since it was recorded.

CaseStamp is a documentation tool and does not guarantee any record will be accepted as evidence in a proceeding; admissibility is determined by applicable law.

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