> ## Documentation Index
> Fetch the complete documentation index at: https://docs.truthlocks.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Content similarity check

> Check whether a content hash already has existing public protections.

<div style={{display: 'flex', gap: '0.5rem', alignItems: 'center', marginBottom: '1rem'}}>
  <span style={{padding: '0.25rem 0.5rem', borderRadius: '0.25rem', fontSize: '0.75rem', fontWeight: 600, backgroundColor: '#dbeafe', color: '#1e40af'}}>GET</span>
  <code>/v1/consumer/similarity</code>
</div>

Check whether a SHA-256 content hash already has public protections. Use this before protecting content to detect exact duplicates and avoid re-protecting content that someone else has already registered.

Authentication is optional. When you include an API key, your own protections are excluded from the results so you only see matches from other users.

Only protections with `visibility: "public"` are searched. Private protections are never returned.

### Parameters

<ParamField query="hash" type="string" required>
  SHA-256 hash of the content to check. Must match the hex-encoded hash format used when [protecting content](/api-reference/consumer/mint).
</ParamField>

### Responses

### Response fields

| Field                        | Type    | Description                                                    |
| ---------------------------- | ------- | -------------------------------------------------------------- |
| `content_hash`               | string  | The hash you submitted, echoed back for confirmation.          |
| `exact_match`                | boolean | `true` if at least one public protection exists for this hash. |
| `matches`                    | array   | Up to 10 matching protections, ordered by creation date.       |
| `matches[].attestation_id`   | string  | Attestation ID of the matching protection.                     |
| `matches[].title`            | string  | Title of the matching protection.                              |
| `matches[].category`         | string  | Content category (e.g. `photography`, `code`, `design`).       |
| `matches[].similarity_score` | number  | Always `1.0` for exact hash matches.                           |
| `matches[].protected_at`     | string  | ISO 8601 timestamp when the content was protected.             |
| `matches[].owner_username`   | string  | Public username of the protection owner, if set.               |
| `total`                      | integer | Total number of matches found.                                 |


## OpenAPI

````yaml mint-openapi.yaml GET /v1/consumer/similarity
openapi: 3.0.3
info:
  title: Truthlocks API
  description: >
    Truthlocks is a universal verification infrastructure for documents,
    credentials, and digital assets.

    This specification defines the canonical API for interacting with Truthlocks
    services.


    ## Base URLs

    - **Production**: `https://api.truthlocks.com`

    - **Sandbox**: `https://sandbox-api.truthlocks.com`


    ## Authentication

    - **API Keys**: Use `X-API-Key` header for machine-to-machine operations

    - **Bearer Tokens**: Use `Authorization: Bearer <jwt>` for user-initiated
    operations


    ## Tenant Identity

    In production, tenant identity is derived from the authenticated context
    (API key or JWT).

    The `X-Tenant-ID` header is ignored in production to prevent spoofing.
  version: 1.0.0
  contact:
    name: Truthlocks Support
    url: https://truthlocks.com/support
    email: support@truthlocks.com
servers:
  - url: https://api.truthlocks.com
    description: Production API
  - url: https://sandbox-api.truthlocks.com
    description: Sandbox Environment
security:
  - APIKey: []
tags:
  - name: Authentication
    description: API key and token management
  - name: Issuers
    description: Issuer registration and trust management
  - name: Keys
    description: Cryptographic key management for issuers
  - name: Attestations
    description: Attestation lifecycle (mint, revoke, supersede)
  - name: Verification
    description: Attestation verification and proof bundles
  - name: Governance
    description: Issuer governance workflows (admin only)
  - name: Identity
    description: Organization, user, and role management
  - name: Audit
    description: Audit event queries
  - name: Platform
    description: Platform administration (super admin only)
  - name: Platform Review
    description: Staff review workflows for issuer applications
  - name: Tenant Console
    description: Tenant profile and lifecycle endpoints
  - name: Health
    description: Service health and readiness endpoints
  - name: Risk
    description: Risk signal ingestion and fraud detection
  - name: Risk Enforcement
    description: Risk enforcement actions — block, challenge, quarantine, and configuration
  - name: Billing
    description: Billing, subscription, and addon management
  - name: Machine Identity
    description: >-
      Machine Agent Identity Protocol (MAIP) — agent registration, sessions,
      trust, witness, compliance, orchestration, and observability
externalDocs:
  description: Transparency read-only API (separate service spec)
  url: >-
    https://github.com/truthlocks/truthlock/blob/main/docs/transparency/openapi.yaml
paths:
  /v1/consumer/similarity:
    get:
      tags:
        - Consumer
      summary: Get similarity score
      description: >-
        Returns content similarity scores for the authenticated consumer's
        portfolio.
      operationId: consumer.similarity
      responses:
        '200':
          description: Similarity scores
          content:
            application/json:
              schema:
                type: object
                properties:
                  scores:
                    type: array
                    items:
                      type: object
                      properties:
                        attestation_id:
                          type: string
                        similarity:
                          type: number
                        match_type:
                          type: string
        '401':
          description: Authentication required
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorEnvelope'
      security:
        - APIKey: []
components:
  schemas:
    ErrorEnvelope:
      type: object
      required:
        - code
        - message
        - http_status
      properties:
        code:
          type: string
          description: Machine-readable error code
          enum:
            - AUTH_REQUIRED
            - AUTH_INVALID
            - PERMISSION_DENIED
            - TENANT_IDENTITY_UNVERIFIED
            - NOT_FOUND
            - VALIDATION_ERROR
            - CONFLICT
            - PAYLOAD_TOO_LARGE
            - RATE_LIMIT_EXCEEDED
            - QUOTA_EXCEEDED
            - SERVICE_UNAVAILABLE
            - INTERNAL_ERROR
        message:
          type: string
          description: Human-readable error message
        http_status:
          type: integer
          description: HTTP status code
        retry_after_ms:
          type: integer
          description: Milliseconds to wait before retrying (for rate limits)
        details:
          type: object
          description: Additional error context
      example:
        code: AUTH_REQUIRED
        message: Authentication required
        http_status: 401
  securitySchemes:
    APIKey:
      type: apiKey
      in: header
      name: X-API-Key
      description: API key for machine-to-machine authentication

````