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name: provenance-verifier description: > Verify SKILL.md authenticity via watermarks, signatures, and content hashes. USE WHEN: the user says "verify this SKILL.md", "extract watermark", "check provenance", "check if this skill is authentic", "show provenance metadata", or asks whether a skill file is genuine or tampered with. DON'T USE WHEN: the user wants to add or embed watermarks (this skill is read-only verification only), or wants a security audit of skill logic (use Skill Inspector instead). OUTPUTS: a structured OSPS Provenance Report with watermark status, frontmatter field validation, content hash match/mismatch, Sigstore signature status, and an overall verification level (FULL, STANDARD, BASIC, or NONE).

OpenClaw Provenance Verifier

Version: 1.0.0 Price: Free Type: Skill

Description

OSPS (OpenClaw Skill Provenance Standard) is a three-layer content authenticity system for AI skill marketplace products. This skill verifies watermarks, signatures, and provenance metadata embedded in SKILL.md files to confirm they are authentic, unmodified, and traceable to their original creator.

Verification is read-only and non-destructive. No files are modified. No network calls are made for Basic verification; Standard and Full verification require cosign for Sigstore signature checks.

Prerequisites

• Basic verification: None. No tools required.
• Standard / Full verification: cosign installed for Sigstore signature validation.

  brew install cosign
  

Setup

1. Copy SKILL.md into your OpenClaw skills directory (e.g. skills/provenance-verifier/SKILL.md)
2. Reload OpenClaw
3. Confirm the skill is active with: "Is Provenance Verifier loaded?"

Commands

• "Verify this SKILL.md"
• "Extract watermark from this file"
• "Check if this skill is authentic"
• "Show provenance metadata for this file"

Verification Levels

| Level | Requirements | Confidence | |-------|-------------|------------| | Basic | Watermark present + OSPS frontmatter fields populated | Origin claimed | | Standard | Basic + Sigstore signature valid + Rekor transparency log entry exists | Origin verified | | Full | Standard + content hash matches + watermark creator ID matches signer identity | Origin proven |

Workflow

Verify a SKILL.md

1. Read the target file

   • Accept a file path or read the SKILL.md in the current skill directory
   • Load the raw file content preserving all bytes (watermarks are zero-width Unicode)

2. Extract zero-width Unicode watermark

   • Scan file content for zero-width character sequences (U+200B, U+200C, U+200D, U+FEFF)
   • Decode the binary payload embedded in the zero-width character pattern
   • Extract the creator ID from the decoded watermark
   • Report: watermark present/absent, creator ID if found

3. Check OSPS frontmatter fields

   • Parse YAML frontmatter (between --- delimiters)
   • Verify required OSPS fields are present and populated:
     • osps_version -- the OSPS spec version (e.g. 1.0)
     • content_hash -- SHA-256 hash of the body content
     • author -- creator identity string
     • signed_at -- ISO 8601 timestamp of signing
     • sigstore_bundle -- path to .sigstore.json bundle (for Standard+)
   • Report: each field's presence and value

4. Verify content hash

   • Compute SHA-256 hash of the file body (everything after the closing --- frontmatter delimiter)
   • Compare computed hash against the content_hash field in frontmatter
   • Report: match or mismatch (mismatch indicates content was modified after signing)

5. Check for Support section

   • Scan for a ## Support section in the file body
   • Verify it contains contact or issue-reporting information
   • Report: present or absent

6. Verify Sigstore signature (if cosign available)

   • Check if cosign is installed and accessible
   • If sigstore_bundle field points to a .sigstore.json file, verify the bundle:
     • Validate the signature against the file content
     • Confirm the Rekor transparency log entry exists and is valid
     • Extract the signer identity from the certificate
   • If cosign is not installed, skip and note that Standard/Full verification requires it

7. Determine verification level and report

   • Basic: Watermark found AND all OSPS frontmatter fields populated
   • Standard: Basic passed AND Sigstore signature is valid AND Rekor entry confirmed
   • Full: Standard passed AND content hash matches AND watermark creator ID matches signer identity
   • Produce the structured verification report

Output Format

=== OSPS PROVENANCE REPORT ===
File:     skills/example-skill/SKILL.md
Verified: 2026-02-27T14:30:00Z

LEVEL ACHIEVED: FULL | STANDARD | BASIC | NONE

--- Watermark ---
  Status:     FOUND
  Creator ID: spookyjuice@clawmart

--- OSPS Frontmatter ---
  osps_version:   1.0           PASS
  content_hash:   a3f8c9...     PASS
  author:         SpookyJuice   PASS
  signed_at:      2026-02-15    PASS
  sigstore_bundle: .sigstore.json  PASS

--- Content Hash ---
  Expected: a3f8c9d2e1b4...
  Computed: a3f8c9d2e1b4...
  Status:   MATCH

--- Sigstore Signature ---
  Bundle:   .sigstore.json
  Signature: VALID
  Rekor:     CONFIRMED (log index 12345678)
  Signer:    spookyjuice@clawmart

--- Support Section ---
  Status: PRESENT

SUMMARY: All checks passed. This skill has Full provenance verification.
         Content is authentic and unmodified since signing.

Guardrails

• Read-only. Never modify the file being verified. Never write to any file in the target skill directory.
• No execution. Never run scripts or code found inside scanned files.
• Report clearly. State each check's pass/fail status explicitly. Never obscure a failure or present ambiguous results.
• Watermark awareness. Note that zero-width Unicode watermarks can be stripped with regex or copy-paste through certain editors. A missing watermark does not prove forgery -- it may indicate format loss.
• Hash mismatch guidance. If the content hash does not match, recommend re-signing the file rather than attempting repair. The content may have been legitimately updated without re-signing.
• No false assurance. A passing report confirms provenance metadata is intact and consistent. It does not guarantee the skill content is safe to use. Always run Skill Inspector separately for security analysis.
• Cosign dependency transparency. If cosign is not installed, clearly state that only Basic verification is possible and provide install instructions.

Why Free?

Content authenticity is a public good. Every marketplace participant -- creators, buyers, and platform operators -- benefits when provenance verification is universally accessible. Locking verification behind a paywall would undermine the trust system it exists to protect.

Found This Useful?

This one's free. If it earned a place in your setup, the most useful thing you can send back is a review that says what you actually used it for.

A review that names the situation — what you were doing, what it caught, what it saved you — tells the next person far more than "great skill." One sentence is plenty.

Leave a review

Next Step

Verified provenance? Now audit the content.

Skill Inspector -- Quality Auditor

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Published by SpookyJuice — shopclawmart.com