Yes, the C2PA TIFF tag is registered with Adobe and specific details on TIFF embedding at https://spec.c2pa.org/specifications/specifications/2.3/specs/C2PA_Specification.html#_embedding_manifests_into_tiff_based_assets
TIFF already supports using IFDs for things other than images - consider ICC profiles, for example. Leonard From: Even Rouault <[email protected]> Date: Monday, March 2, 2026 at 1:43 PM To: Leonard Rosenthol <[email protected]>, [email protected] <[email protected]> Subject: Re: [Tiff] Libtiff failing on TIFFs with embedded C2PA Manifests? EXTERNAL: Use caution when clicking on links or opening attachments. Seems to me like a weird design to hijack a IFD (*Image* File Directory) to put something different in it. Why not having used a TIFF tag in the first IFD for example ? But I assume my question is mostly moot now if that C2PA spec has progressed beyond being a draft? I guess if someone wanted those files to be read by libtiff, the best course of action would be to silently ignore that final IFD, or just emit a warning instead of an error ( I assume there must be a spefic TIFF tag to recognize it?) Even Le 02/03/2026 à 19:30, Leonard Rosenthol via Tiff a écrit : A person reported (https://github.com/contentauth/c2pa-rs/issues/1894) that libtiff-based apps are failing to process TIFF files with embedded C2PA Manifests (https://c2pa.org/specifications/specifications/2.3/specs/C2PA_Specification.html). I’ve commented there that I don’t agree with their position on the topic, nor can I verify their results. Would love for any/all of you to comment on the situation - either here or there. Thanks, Leonard _______________________________________________ Tiff mailing list [email protected]<mailto:[email protected]> https://lists.osgeo.org/mailman/listinfo/tiff -- http://www.spatialys.com<http://www.spatialys.com/> My software is free, but my time generally not.
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