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Limitations

SignedShot provides strong guarantees about capture authenticity, but it's important to understand what it doesn't protect against.

What SignedShot Does NOT Prove​

Content Truthfulness​

SignedShot proves a device captured specific content — not that the content depicts reality.

Example: Photographing a printed deepfake, a TV screen showing manipulated video, or a staged scene produces a valid SignedShot capture. The capture is authentic; the subject may not be.

Implication: SignedShot is about provenance (where did this come from?), not truth (is this real?).

Scene Authenticity​

SignedShot doesn't verify what the camera is pointed at.

Example: An attacker could:

  • Display AI-generated content on a monitor and photograph it
  • Print a fake document and capture it
  • Stage a scene with actors

All would produce valid captures.

Pre-Capture Manipulation​

If content is manipulated before being photographed, SignedShot cannot detect it.

Example: A document could be forged, printed, then photographed with SignedShot. The capture is authentic; the document is not.

Identity of Photographer​

SignedShot identifies the device, not the person using it.

Example: Anyone with physical access to a registered device can create valid captures. There's no biometric or identity verification.

Implication: "This device captured this" ≠ "This person captured this"

Technical Limitations​

Compromised Devices​

Rooted/Jailbroken Devices:

  • Secure Enclave still protects keys on most rooted devices
  • However, sophisticated attacks may be possible
  • Attestation (app_check) may fail on some rooted devices

Physical Attacks:

  • Sophisticated hardware attacks on Secure Enclave are theoretically possible
  • Requires physical access and specialized equipment
  • Not practical for most threat scenarios

Sandbox Mode​

sandbox mode provides NO security guarantees:

  • No attestation is performed
  • Any device can register
  • Signatures are still valid, but trust is minimal

Use only for:

  • Development and testing
  • Demos and proof-of-concept
  • Non-critical applications

Network Dependency​

SignedShot requires network connectivity for:

  • Device registration (once)
  • Creating capture sessions
  • Exchanging nonces for trust tokens

Implication: Fully offline capture is not currently supported. The media integrity layer (hash + signature) works offline, but the capture trust layer (JWT) requires server communication.

Key Loss​

If a device is lost, wiped, or replaced:

  • The Secure Enclave keys are lost
  • Previous captures remain verifiable (public key is in sidecar)
  • New captures require re-registration on the new device

Server Dependency​

SignedShot's capture trust layer depends on the API server:

  • Server issues JWTs
  • Server manages sessions and nonces
  • JWKS provides verification keys

Implication: If the server is unavailable, new captures can't get trust tokens. Existing captures remain verifiable as long as JWKS is cached or accessible.

Platform Limitations​

iOS Only (Currently)​

The SDK currently supports iOS only.

Roadmap: Android support is planned for post-launch.

Photos Only (Currently)​

Video support is in development.

Current state: The protocol supports video (SHA-256 works on any byte stream), but the iOS SDK currently supports photos only.

Comparison to Detection​

SignedShot takes a fundamentally different approach than AI detection:

ApproachWhat it doesLimitations
AI DetectionAnalyzes content for signs of manipulationArms race with generators; false positives/negatives
SignedShotProves content came from a verified sourceDoesn't detect pre-capture manipulation

SignedShot's advantage: No arms race. Cryptographic proofs don't become less secure as AI improves.

SignedShot's limitation: Only works for content captured through the SignedShot flow. Doesn't help with existing content.

Responsible Use​

What Verifiers Should Communicate​

When displaying SignedShot verification results, be clear about what was verified:

Good:

"This media was captured on a verified device on [date] and has not been modified since."

Misleading:

"This media is authentic and real."

Combine with Other Evidence​

SignedShot is one piece of evidence, not the whole story:

  • Cross-reference with other sources
  • Consider context and circumstances
  • Apply editorial or investigative judgment
  • Use SignedShot as part of a verification workflow

Summary​

SignedShot ProvesSignedShot Does NOT Prove
Content hasn't been modifiedContent depicts reality
Captured on a specific deviceIdentity of photographer
Captured at a specific timeScene wasn't staged
App passed attestationDevice wasn't compromised

Next Steps​