Media Assertions

Look up assertions about media artifacts. MIR records who made each assertion, not whether it's accurate.

Search by artifact

or

Drop or paste a file here
File is hashed locally - never uploaded

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How to interpret this

  • MIR records who made each assertion
  • MIR does not verify content accuracy
  • Conflicting assertions indicate a dispute - review issuer identities
  • Absence of assertions is not evidence of anything

What are assertions?

Assertions are cryptographically-signed statements about media files. Organizations register with MIR, then sign claims like "we published this" or "this is not from us."

Assertions are opt-in, affirmative acts. MIR does not label, detect, or accuse. Unasserted media simply remains unasserted.

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Signed by issuers

Each assertion is signed with the issuer's private key. Anyone can verify the signature using their public key.

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Lookup by hash

Compute a file's SHA-256 hash and query MIR. If the hashes match, the files are identical.

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Files never uploaded

MIR stores only 64-character hashes. Your media never leaves your device.

Assertion types

ISSUED_BY "We published this"
NOT_ISSUED_BY "This is not from us" — deepfake defense
DISPUTE "We dispute an existing assertion on this artifact"
ROLE_SCOPE "Created by [department], not official communications"
INTENT "This is parody / training material / marketing"
METHOD "AI-generated / human-created / hybrid"

Apply to become an issuer | Browser Signer

Understanding Hash-Based Lookup

MIR uses SHA-256 hashes to identify media files. This means byte-for-byte identical files produce the same hash. Any modification — even re-encoding — produces a different hash.

Works well for

  • Original files shared via direct download
  • PDFs and documents (not re-encoded)
  • Press releases hosted on your own site
  • Repudiating fakes ("this deepfake is not from us")

Hash won't match after

  • Platform re-encoding (YouTube, TikTok, Instagram)
  • Screenshots or screen recordings
  • Re-compressed or resized files

Include the hash, verification link, or QR code with your social media posts so viewers can verify with the MIR lookup.

For issuers

Assert against your original file before uploading to any platform. Include the hash or verification link in your caption or description. Viewers paste it into MIR to confirm your assertion exists — no need to download the original file.