Provenance: watermarks + C2PA as complementary layers
modality x mechanism
text
SynthID-text (Kirchenbauer)
green/red token bias
paraphrase-vulnerable
image
SynthID + Stable Signature
latent-decoder fingerprint
fine-tune-vulnerable
audio
SynthID-audio
spectral signal
re-encoding-resistant
video
SynthID-video (Veo)
frame + temporal signal
frame-rate robust
C2PA 2.2: cryptographically signed metadata
provenance chain
creator, ingredients, transformations
signed manifest
tamper-evident; can be stripped
layered properties
watermark survives compression, cropping, re-encoding; does NOT survive paraphrase or adversarial fine-tune.
C2PA metadata carries richer provenance; CAN be stripped but its absence signals suspicion.
regulatory: EU AI Act Article 50 (effective Aug 2026) requires deepfake labelling; Transparency Code final Jun 2026.