verifiable-credentials-zk SKILL.md skillA
verifiable-credentials-zk from sparq-org/sparq is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add sparq-org/sparq/verifiable-credentials-zk@git:20260612.13b231cPins git:20260612.13b231c in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- sparq-org/sparq
- Path
.claude/skills/verifiable-credentials-zk/SKILL.md- Versions recorded
- 1
- Latest version
- git:20260612.13b231c, committed Jun 12, 2026
- Size
- 4,628 bytes
- Repository stars
- 13
- License
- MIT
Patterns for handling W3C Verifiable Credentials inside a zero-knowledge pipeline — signature scheme trade-offs (BBS+ vs SD-JWT-VC vs EdDSA), commitment schemes (Pedersen, Poseidon), encoding of credential graphs to circuit-friendly representations, domain-separation discipline, and the public-input contract between the credential layer and the Noir circuit. Use when choosing crypto primitives, drafting the assumptions section, or pinning the verifier interface.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Verifiable Credentials in a ZK pipeline Patterns for the cryptographic seam between W3C Verifiable Credentials and the Noir circuits in this workspace. ## Signature scheme trade-offs | Scheme | Native selective disclosure? | In-circuit verification cost | Ecosystem alignment | When to pick | | --- | --- | --- | --- | --- | | **BBS+** | Yes (per-message blinding) | High — pairing-friendly group ops are heavy in BN254 / Grumpkin | Strong (W3C VC, IRTF draft) | When selective disclosure is the dominant feature and the verifier outside the circuit can do the heavy lifting (verifying a BBS+ proof of knowledge, not the signature directly). | | **SD-JWT-VC** | Yes (salted-hash disclosures) | Moderate — hashing only | Strong (IETF, OAuth ecosystem) | When you want JWT-shaped tokens, simple disclosures, no pairings. | | **EdDSA** | No (sign whole document) | Low — Ed25519 verifications are cheap | Universal | When the whole credential is disclosed, or when the prover holds a separate "compiled" representation that the SPARQL evaluator commits to. | For the paper's first version, **EdDSA + a separate prover-side commitment** is the simplest defensible choice. BBS+ becomes …
Read the whole file at its exact version.
How to install
mdr add sparq-org/sparq/verifiable-credentials-zk@sha256:8073f98f6221722eThe line at the top of this page pins the label git:20260612.13b231c, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_eu5pkw3iionoewjg)
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Versions
The registry has recorded 1 version of this file, committed on Jun 12, 2026.
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (4628 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
sparq-org/sparq · 13 stars · license MIT · pushed 2026-11-05 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_eu5pkw3iionoewjg GET https://markdownregistry.com/api/v1/resolve?ref=sparq-org/sparq/verifiable-credentials-zk GET https://markdownregistry.com/api/v1/blob/8073f98f6221722eb0302f100ade9412dadbea50d55cb02f9b4d042f3c65d24d
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.