Resolves the tension between steganography (strip everything to
protect sources) and attestation (preserve evidence of provenance):
- New soosef.metadata module with extract_and_classify() and
extract_strip_pipeline() — classifies EXIF fields as evidentiary
(GPS, timestamp — valuable for proving provenance) vs dangerous
(device serial, firmware — could identify the source)
- Drop box now uses extract-then-strip: attests ORIGINAL bytes (hash
matches what source submitted), extracts evidentiary EXIF into
attestation metadata, strips dangerous fields, stores clean copy
- Attest route gains strip_device option: when enabled, includes
GPS/timestamp in attestation but excludes device serial/firmware
- Stego encode unchanged: still strips all metadata from carriers
(correct for steganography threat model)
The key insight: for stego, the carrier is a vessel (strip everything).
For attestation, EXIF is the evidence (extract, classify, preserve
selectively). Both hashes (original + stripped) are recorded so the
relationship between raw submission and stored copy is provable.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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