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Impatient? LSB death, compression killers, then an honest method pick.
The night-before ritual: hygiene, map, carrier, whole-pack audit.
Evidence first, takedown second, drill it with case files.
Start here
Core
- 2 · Core8 min
How invisible watermarking traces a leak
Each subscriber receives a file that looks identical but carries a private recipient ID. When a leak appears, you recover that ID from the exact downloaded file and match it to your delivery record.
One master becomes N unique copies, one per recipient_id.Start chapter → - 8 · Core7 min
The CSV is the map. Dirty map, no attribution.
One duplicate recipient_id means two humans share one fingerprint. Break a list live, watch the collision, fix it, and confirm every ID names exactly one human.
recipient_id must map 1:1 to the human receiving that copy.Start chapter →
Hands-on
- 3 · Hands-on12 min
LSB looks perfect until you save as JPEG
Least-significant-bit hiding is invisible and trivially destroyed. Embed a message in your browser, export PNG versus JPEG, and watch the payload survive once and die once.
LSB survives untouched PNGs and dies on any JPEG re-encode.Start chapter → - 4 · Hands-on10 min
Compression, crops and screenshots: the three killers
Drag three sliders and watch similarity collapse. Re-encodes change bytes while the image still looks the same, crops delete evidence outright, screenshots create a brand-new bitmap.
JPEG quality under ~70 visibly degrades fragile marks while the image still looks fine.Start chapter → - 7 · Hands-on8 min
Tags travel with files. Strip them before delivery.
Scan a phone photo, count the EXIF and GPS tags riding along, strip them with a canvas re-export, and verify zero. All local.
Camera JPGs carry GPS, device IDs and edit history by default.Start chapter → - 9 · Hands-on9 min
See the frequencies robust methods hide in
Your image as 8×8 cosine blocks: heatmap the mid-band hiding space, then quantize it away and watch detail dissolve in the exact order JPEG kills.
Images are sums of cosine waves; JPEG keeps the big slow ones.Start chapter → - 10 · Hands-on8 min
Will this image carry a mark?
Texture and edge analysis scores your photo as a watermark carrier. Test your flattest pack image. The gap between best and worst is your real risk spread.
Texture and edges are hiding space; flat gradients starve fragile methods.Start chapter → - 11 · Hands-on9 min
Audit the whole pack the night before
Drop up to 20 images: dimensions, metadata tags and carrier scores in one table, exportable as a release-notes CSV. Batch thinking without the app.
Audit packs as tables, not vibes: every file gets dims, tags, carrier.Start chapter → - 12 · Hands-on7 min
Write a takedown notice that works
Platform-tailored notice generator with an evidence checklist attached. General information, not legal advice. Get counsel for high-value disputes.
Exact post URLs, not channel homepages: precision gets removals.Start chapter →
Decision
Field manual
- 6 · Field manual9 min
Limits, evidence and what to do after a leak
No watermark survives everything. Learn the evidence chain that still gives you options: preserve the file, compare, audit metadata, and only then attribute.
Save the exact file, never a screenshot, and log URL plus time immediately.Start chapter → - 13 · Field manual12 min
Three cases. Download. Investigate. Reveal.
Fictional training scenarios with real fixture files: a Telegram forward, a cropped repost, a dirty CSV. Work each with the free tools, then reveal the solution.
Triage before attribution: compare, audit, then decide on Inspect.Start chapter →
How to work the labs
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- Start at chapter 3 if you are impatient: LSB fragility lab breaks a hidden message in 60 seconds.
- Use the sample image first. No uploads of any kind, same lesson. Then try one of your own exports.
- Read the caveats. Every demo has an "Honest limits" box. Knowing what a demo does not prove is the actual skill.
Diagrams are educational illustrations, not Foddo internals. Foddo implements LSB, JPEG DCT, TrustMark, Robust Transform and WAM locally with different survival profiles.