nips/XX.md

NIP-XX: ProofMode - Cryptographic Video Verification

draft optional

Abstract

This NIP defines a standard for attaching cryptographic proof manifests to video events (NIP-71) to enable verification of video authenticity, recording continuity, and device integrity. ProofMode allows viewers to verify that a video was recorded on a specific device at a specific time without editing or tampering.

Motivation

Social media platforms are increasingly vulnerable to deepfakes, edited videos, and synthetic media. While blockchain timestamping exists, it doesn't prove video continuity or prevent frame-level manipulation. ProofMode solves this by:

1. Frame-level verification - SHA256 hashes of captured frames prove recording continuity
2. Hardware attestation - iOS App Attest and Android Play Integrity verify the recording device
3. Cryptographic signing - PGP signatures ensure manifest authenticity
4. Tamper detection - Any edit to the video invalidates the proof chain
5. Segment tracking - Recording pauses are documented with sensor data

Specification

Event Tags

ProofMode data is attached to video events (typically Kind 34236) using the following tags:

Required Tags

• ["verification", "<level>"] - Verification level (see Verification Levels below)
• ["proofmode", "<manifest_json>"] - Complete ProofManifest as compact JSON

Optional Tags

• ["device_attestation", "<token>"] - Hardware attestation token from iOS App Attest or Android Play Integrity
• ["pgp_fingerprint", "<fingerprint>"] - PGP public key fingerprint used to sign the manifest

Verification Levels

The verification tag indicates the strength of cryptographic proof:

• verified_mobile - Highest level: has device attestation + PGP signature + complete manifest
• verified_web - Medium level: has PGP signature + complete manifest (no hardware attestation)
• basic_proof - Low level: has proof data but no cryptographic signature
• unverified - No meaningful proof data

ProofManifest Structure

The proofmode tag contains a JSON object with the following structure:

{
  "sessionId": "<unique_session_id>",
  "challengeNonce": "<16_char_nonce>",
  "vineSessionStart": "<ISO8601_timestamp>",
  "vineSessionEnd": "<ISO8601_timestamp>",
  "totalDuration": 6500,
  "recordingDuration": 6000,
  "segments": [
    {
      "segmentId": "<segment_id>",
      "startTime": "<ISO8601_timestamp>",
      "endTime": "<ISO8601_timestamp>",
      "duration": 3000,
      "frameHashes": [
        "<sha256_hash_1>",
        "<sha256_hash_2>",
        "..."
      ],
      "frameTimestamps": [
        "<ISO8601_timestamp_1>",
        "<ISO8601_timestamp_2>",
        "..."
      ],
      "sensorData": {
        "accelerometer": {"x": 0.1, "y": 0.2, "z": 9.8},
        "gyroscope": {"x": 0.01, "y": 0.02, "z": 0.01}
      }
    }
  ],
  "pauseProofs": [
    {
      "startTime": "<ISO8601_timestamp>",
      "endTime": "<ISO8601_timestamp>",
      "duration": 500,
      "sensorData": {
        "timestamp": "<ISO8601_timestamp>",
        "accelerometer": {"x": 0.1, "y": 0.2, "z": 9.8},
        "gyroscope": {"x": 0.01, "y": 0.02, "z": 0.01},
        "magnetometer": {"x": 45.0, "y": 12.0, "z": -30.0},
        "light": 150.0
      },
      "interactions": [
        {
          "timestamp": "<ISO8601_timestamp>",
          "interactionType": "touch",
          "coordinates": {"x": 180, "y": 640},
          "pressure": 0.5
        }
      ]
    }
  ],
  "interactions": [
    {
      "timestamp": "<ISO8601_timestamp>",
      "interactionType": "start|stop|touch",
      "coordinates": {"x": 180, "y": 640},
      "pressure": 0.5,
      "metadata": {}
    }
  ],
  "finalVideoHash": "<sha256_hash_of_complete_video>",
  "deviceAttestation": {
    "token": "<platform_specific_attestation_token>",
    "platform": "iOS|Android|Web",
    "deviceId": "<device_identifier>",
    "isHardwareBacked": true,
    "createdAt": "<ISO8601_timestamp>",
    "challenge": "<challenge_nonce>",
    "metadata": {
      "attestationType": "app_attest|play_integrity|fallback",
      "deviceInfo": {
        "platform": "iOS",
        "model": "iPhone 15 Pro",
        "version": "17.0",
        "manufacturer": "Apple"
      }
    }
  },
  "pgpSignature": {
    "signature": "-----BEGIN PGP SIGNATURE-----\n...\n-----END PGP SIGNATURE-----",
    "publicKey": "-----BEGIN PGP PUBLIC KEY BLOCK-----\n...\n-----END PGP PUBLIC KEY BLOCK-----",
    "publicKeyFingerprint": "1A2B3C4D5E6F7890..."
  }
}

Field Descriptions

Core Fields

• sessionId - Unique identifier for the recording session
• challengeNonce - Random nonce generated at session start, used in device attestation to prevent replay attacks
• vineSessionStart / vineSessionEnd - Recording session boundaries
• totalDuration - Total elapsed time in milliseconds (including pauses)
• recordingDuration - Actual recording time in milliseconds (excluding pauses)

Segments

Recording can be paused and resumed, creating multiple segments. Each segment contains:

• segmentId - Unique segment identifier
• startTime / endTime - Segment boundaries
• frameHashes - Array of SHA256 hashes of captured video frames
• frameTimestamps - Timestamps when each frame was captured (optional)
• sensorData - Device sensor readings during recording (optional)

Pause Proofs

When recording is paused, sensor data is collected to prove device continuity:

• startTime / endTime - Pause boundaries
• sensorData - Sensor readings during pause (accelerometer, gyroscope, magnetometer, light)
• interactions - User touch/tap events during pause

Interactions

User interactions recorded throughout the session:

• timestamp - When interaction occurred
• interactionType - Type of interaction (start, stop, touch)
• coordinates - Screen coordinates of interaction
• pressure - Touch pressure (optional)

Final Video Hash

• finalVideoHash - SHA256 hash of the complete rendered video file

Device Attestation

Platform-specific hardware attestation proving the device is genuine:

• iOS: Uses App Attest API (iOS 14+)
• Android: Uses Play Integrity API
• Web/Other: Fallback software attestation

Fields:

• token - Platform-specific attestation token
• platform - Operating system (iOS, Android, Web)
• deviceId - Device identifier
• isHardwareBacked - Whether attestation uses hardware security module
• challenge - Challenge nonce used in attestation (matches challengeNonce)
• metadata - Platform-specific attestation details

PGP Signature

Cryptographic signature of the entire manifest:

• signature - PGP signature in ASCII-armored format
• publicKey - PGP public key in ASCII-armored format
• publicKeyFingerprint - Key fingerprint for quick lookup

Implementation

Recording Phase

1. Start Session

   • Generate unique sessionId and challengeNonce
   • Request hardware device attestation with challenge nonce
   • Initialize ProofMode session

2. Capture Frames

   • During recording, periodically capture video frames
   • Generate SHA256 hash of each frame
   • Store frame hashes with timestamps
   • Optionally collect sensor data (accelerometer, gyroscope, etc.)

3. Handle Pauses

   • When recording pauses, stop current segment
   • Begin collecting pause proof data (sensor readings, interactions)
   • When resuming, start new segment

4. Finalize Session

   • Stop recording and close final segment
   • Hash complete video file
   • Compile ProofManifest with all segments, pauses, and interactions
   • Sign manifest with PGP private key
   • Attach ProofManifest to video event as tags

Verification Phase

To verify a ProofMode video, clients should:

1. Extract ProofManifest

   • Parse proofmode tag from video event
   • Extract deviceAttestation and pgpSignature from separate tags

2. Verify PGP Signature

   • Extract PGP public key from manifest
   • Verify signature of manifest JSON
   • Check public key fingerprint matches pgp_fingerprint tag

3. Verify Device Attestation (if present)

   • Validate attestation token against platform-specific APIs
   • Verify challenge nonce matches manifest challengeNonce
   • Check attestation timestamp is recent (within 24 hours of recording)

4. Verify Frame Hashes (advanced)

   • Re-encode video to extract individual frames
   • Generate SHA256 hashes of extracted frames
   • Compare against hashes in manifest segments
   • Verify frame count and timestamps match recording duration

5. Verify Recording Continuity

   • Check that segment timestamps are contiguous
   • Verify pause durations match gaps between segments
   • Validate total recording duration matches video length

6. Display Verification Badge

   • verified_mobile - Show "Verified" badge with hardware attestation icon
   • verified_web - Show "Signed" badge
   • basic_proof - Show "Basic Proof" indicator
   • unverified - No badge or "Unverified" indicator

Example Event

{
  "kind": 34236,
  "pubkey": "...",
  "created_at": 1730326800,
  "tags": [
    ["d", "unique-video-identifier"],
    ["title", "My Verified Video"],
    ["url", "https://media.example.com/video.mp4", "720x1280"],
    ["thumb", "https://media.example.com/thumb.jpg", "720x1280"],
    ["duration", "6"],
    ["verification", "verified_mobile"],
    ["proofmode", "{\"sessionId\":\"session_1730326800000_1234\",\"challengeNonce\":\"a1b2c3d4e5f6789\",\"vineSessionStart\":\"2025-10-30T10:00:00.000Z\",\"vineSessionEnd\":\"2025-10-30T10:00:06.500Z\",\"totalDuration\":6500,\"recordingDuration\":6000,\"segments\":[{\"segmentId\":\"segment_1\",\"startTime\":\"2025-10-30T10:00:00.000Z\",\"endTime\":\"2025-10-30T10:00:06.000Z\",\"frameHashes\":[\"e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855\"]}],\"pauseProofs\":[],\"interactions\":[{\"timestamp\":\"2025-10-30T10:00:00.000Z\",\"interactionType\":\"start\",\"coordinates\":{\"x\":180,\"y\":640}}],\"finalVideoHash\":\"d4e5f6a7b8c9...\"}"],
    ["device_attestation", "AAABBBCCC..."],
    ["pgp_fingerprint", "1A2B3C4D5E6F7890..."]
  ],
  "content": "Check out this verified video!",
  "sig": "..."
}

Security Considerations

Threat Model

ProofMode protects against:

• ✅ Post-recording video editing - Frame hashes detect any modifications
• ✅ Deepfakes and synthetic videos - Hardware attestation proves real device
• ✅ Timestamp manipulation - Device attestation includes trusted timestamps
• ✅ Replay attacks - Challenge nonce prevents reuse of attestations

ProofMode does NOT protect against:

• ❌ Screen recording - A user can screen-record another video
• ❌ Camera lens manipulation - Physical objects placed in front of camera
• ❌ Compromised devices - Rooted/jailbroken devices may forge attestations
• ❌ Social engineering - User can intentionally create misleading content

Privacy Considerations

• Device Identifiers: The deviceId field may be sensitive. Clients should:

  • Hash or truncate device IDs before publishing
  • Allow users to opt-out of device attestation
  • Clearly indicate when ProofMode is active

• Sensor Data: Accelerometer and gyroscope data may reveal user location or behavior. Clients should:

  • Allow disabling sensor data collection
  • Sanitize or omit sensitive sensor readings
  • Aggregate sensor data to reduce precision

• PGP Keys: Users should be able to:

  • Rotate PGP keys periodically
  • Revoke compromised keys
  • Use separate keys for different purposes

Verification Best Practices

Verifying clients should:

1. Always check PGP signature - This is the minimum verification
2. Validate device attestation when present - But gracefully handle missing/invalid attestations
3. Display verification level prominently - Users should understand confidence level
4. Cache verification results - Re-verification is expensive
5. Handle expired attestations - Attestations may expire after 24-48 hours
6. Warn on missing proofs - But don't assume malice if ProofMode is absent

Reference Implementation

OpenVine provides a complete reference implementation:

• Recording: ProofModeSessionService in OpenVine mobile app
• Publishing: VideoEventPublisher adds ProofMode tags to Nostr events
• Verification: ProofModeHelpers and verification UI components

Source: https://github.com/openvine/openvine

Backwards Compatibility

This NIP is fully backwards compatible:

• Events without ProofMode tags are treated as unverified
• Older clients ignore ProofMode tags
• ProofMode is opt-in - videos without it still work normally

Future Extensions

Possible future enhancements:

1. Witness Signatures - Multiple devices co-sign the same recording
2. Location Proofs - GPS coordinates with cryptographic verification
3. Biometric Proof - Prove human presence during recording
4. Chain of Custody - Track video transfer and handling
5. Selective Disclosure - Zero-knowledge proofs for privacy-preserving verification

References

• NIP-01: Basic protocol flow description
• NIP-71: Video Events
• iOS App Attest
• Android Play Integrity
• ProofMode Original Project

Authors

• Evan Henshaw-Plath (Rabble)

License

This NIP is released into the public domain.