# DDG DID/VC Credential Verifier

> DDG DID/VC Credential Verifier is a paid API for AI agents from agents.daedalusdevelopmentgroup.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-20).

Resolves and cryptographically verifies DID/VC credentials (did:web, did:key), checks Ed25519 signatures, key purposes, validity windows, revocation status, and AIP delegation chains, returning a deterministic verdict with reason codes.

## Facts

- Endpoint: POST https://agents.daedalusdevelopmentgroup.com/v1/identity/verify-credential?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/ddg-did-vc-credential-verifier-391b88e4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Yn55QUyJGJ7GckxksQiVz

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability ddg-did-vc-credential-verifier-391b88e4 -d '<json body>'
```

Example prompt: Can you verify this verifiable credential for me — it's a did:web document with an Ed25519 proof — and tell me whether it's valid, invalid, or unverifiable, along with the reason code?

## When to prefer this

Choose this endpoint when you need a deterministic, cryptographically-signed verification of did:web or did:key credentials with full Ed25519 proof checking, revocation lookup, and AIP delegation chain walking — all in a single API call for $0.01. Prefer it over rolling your own DID resolution when you need a machine-payable, agent-friendly verification service that returns structured reason codes and a signed verdict suitable for audit trails.

## Known failure modes

- DID document cannot be resolved (network error or unknown DID method) → 'unverifiable' verdict with resolution-failure reason code
- Ed25519 signature check fails → 'invalid' verdict with signature-mismatch reason code
- Credential outside validity window → 'invalid' verdict with expired or not-yet-valid reason code
- verificationMethod key purpose mismatch → 'invalid' verdict with key-purpose reason code
- Revocation check returns revoked status → 'invalid' verdict with revocation reason code
- Malformed or missing required credential fields → validation error with schema reason code
- AIP delegation chain scope exceeds parent scope → 'invalid' verdict with scope-overflow reason code

## How this service works

DID/VC credential verification: resolve did:web/did:key (or an inline DID document), check the Ed25519 proof signature, verificationMethod/key-purpose match, validity window, revocation, and walk an AIP delegation chain (scope-subset + validity-nesting). Deterministic valid/invalid/unverifiable verdict with reason codes, Ed25519-signed. $0.01.

## Output

A deterministic verdict of 'valid', 'invalid', or 'unverifiable' accompanied by structured reason codes explaining the outcome. The response is itself Ed25519-signed by DDG, covering signature check results, key purpose match, validity window status, revocation status, and (if applicable) delegation chain scope and nesting validity.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input",
  "output"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object"
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST",
      "PUT",
      "PATCH"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": true
  },
  "output": {
   "type": "object",
   "required": [
    "type",
    "example"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "ok": true
    }
   },
   "additionalProperties": true
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/ddg-did-vc-credential-verifier-391b88e4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agents.daedalusdevelopmentgroup.com](https://www.zero.xyz/host/agents.daedalusdevelopmentgroup.com/llms.txt)