competition-stego-media

1# Competition Stego Media
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3Use this skill only as a downstream specialization after `$ctf-sandbox-orchestrator` is already active and has established sandbox assumptions, node ownership, and evidence priorities. If that has not happened yet, return to `$ctf-sandbox-orchestrator` first.
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5Use this skill when the challenge lives inside a media container, hidden channel, or appended payload rather than a conventional crypto blob.
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7Reply in Simplified Chinese unless the user explicitly requests English.
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9## Quick Start
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111. Confirm the real container type, dimensions, duration, codec, and chunk layout before guessing a hidden layer.
122. Check metadata, thumbnails, sidecar files, and appended trailers before deeper signal-domain work.
133. Rank candidate channels by evidence: alpha, palette, LSB, transform-domain residue, frame order, or container slack.
144. Preserve each extracted layer separately so the transform chain stays reproducible.
155. Stop when the hidden payload is reproduced, not merely suspected.
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17## Workflow
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19### 1. Establish Container Truth
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21- Inspect headers, chunk tables, EXIF or document metadata, container indexes, thumbnails, and file size anomalies.
22- Compare declared format against observed structure to catch polyglots, appended archives, or malformed trailers.
23- Record exact offsets, frame numbers, or channel boundaries that look promising.
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25### 2. Inspect Candidate Channels
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