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Overview

The Certificate API generates official certificates (constancias) that verify an employee has completed the background evaluation process. Certificates include QR codes for third-party validation.
Certificates are generated with encrypted QR codes that allow external organizations to verify authenticity through the Validation API.

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View Certificate

curl -X GET https://api.vlife-dgo.com/Constancia/constanciaView/U2FsdGVkX1...
Generates and displays a certificate with QR code for a completed evaluation.

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Endpoint

GET /Constancia/constanciaView/:constanciaValidacion

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Authentication

Requires active user session (authenticated via session middleware).

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Path Parameters

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constanciaValidacion
string
required
Encrypted validation string that contains the evaluation ID. This same string is used in the QR code for certificate validation.

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Response

Returns an HTML view (constanciaViews/constanciaView) displaying the certificate with:
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user
string
Current user’s name from session.
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QR
string
Base64-encoded QR code image (Data URL format).
data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAA...
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dataConstancia
object
Certificate metadata and validation information.
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Empleado
object
Employee information displayed on certificate.

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QR Code Generation

The QR code is generated using the qrcode library and contains a validation URL: 
import qrcode from 'qrcode';

// Generate validation URL
const urlValidator = `http://asdfytrfdggfg/constanciaValidator/${constanciaValidacion}`;

// Create QR code as Data URL
const QR = await qrcode.toDataURL(urlValidator);
QR Code Properties:
  • Format: PNG image as Data URL
  • Content: Full validation URL with encrypted evaluation ID
  • Purpose: Allow third parties to verify certificate authenticity
  • Validation Endpoint: /Validator/ConstanciaValidator/:cadena

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Database Queries

Get Certificate Data: 
SELECT * FROM tbl_dgo_constancias 
WHERE evalID = ? AND constanciaActivo = 1
Get Employee Data: 
SELECT empleados.empNombreCompleto, empleados.empRFC 
FROM tbl_dgo_evaluaciones evaluaciones
INNER JOIN cat_dgo_empleados empleados 
  ON evaluaciones.empID = empleados.empID
WHERE evaluaciones.evalID = ?

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Decryption Process

The constanciaValidacion parameter is decrypted to retrieve the evaluation ID: 
import ncrypt from 'ncrypt-js';

const ncryptObjet = new ncrypt(keyDecrypt.key);
const decryptedData = ncryptObjet.decrypt(constanciaValidacion);
// decryptedData contains the evalID

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Error Handling

Silent error handling - errors are caught but not displayed to user. The view may render empty or redirect based on error type.
The controller has an empty catch block, which means errors are not properly handled or logged.

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Certificate Data Structure

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Certificate Record

Stored in tbl_dgo_constancias table:
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constanciaID
integer
Auto-increment primary key.
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evalID
integer
Foreign key to evaluation record.
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constanciaValidacion
string
Encrypted validation string (ncrypt-js).
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constanciaCreado
datetime
Timestamp of certificate creation.
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constanciaActivo
integer
Soft delete flag (1 = active, 0 = deleted).

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Certificate Validation Workflow

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Generation Process

  1. Evaluation Complete: Employee completes background evaluation
  2. Generate Certificate: System creates certificate record with validation string
  3. Encrypt ID: Evaluation ID encrypted using ncrypt-js
  4. Create QR Code: QR code generated with validation URL
  5. Display Certificate: HTML view rendered with employee data and QR code

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Validation Process

  1. QR Scan: External party scans QR code on certificate
  2. URL Redirect: QR code redirects to validation endpoint
  3. Decrypt ID: Server decrypts validation string
  4. Query Database: Retrieves certificate and employee data
  5. Display Validation: Shows certificate details and authenticity confirmation
See Document Validation for details on the validation endpoint.

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Certificate Display Format

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Visual Elements

  • Header: Official CEACC Durango logo and letterhead
  • Title: “Constancia de Evaluación” or similar
  • Employee Name: Full name prominently displayed
  • RFC: Tax identifier for verification
  • Issuance Date: Date certificate was generated
  • QR Code: Positioned for easy scanning (typically bottom-right)
  • Validation Text: Instructions for QR code verification
  • Official Signature: Digital or scanned signature of authority
  • Folio Number: Certificate identifier for reference
The certificate view is designed for printing:
  • Standard letter size (8.5” × 11”)
  • Print-friendly styling
  • High-resolution QR code
  • Official color scheme

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QR Code Technical Details

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Library

Package: qrcode (npm) Version: Check package.json in source code Documentation: https://www.npmjs.com/package/qrcode

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Generation Method

await qrcode.toDataURL(urlString)
Returns a Data URL containing a PNG image that can be directly embedded in HTML: 
<img src="{{QR}}" alt="QR Code" />

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QR Code Content

The QR code encodes a full URL: 
http://asdfytrfdggfg/constanciaValidator/U2FsdGVkX1+abc123xyz...
URL Components:
  • Protocol: http:// or https://
  • Domain: System domain (appears to be placeholder in code)
  • Path: /constanciaValidator/
  • Parameter: Encrypted evaluation ID

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Security Features

  • Encryption: Validation string encrypted with ncrypt-js
  • Active Check: Only active certificates (constanciaActivo = 1) validate
  • Database Verification: QR code links to live database record
  • Tamper-Proof: Any modification to encrypted string breaks validation

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Source Code References

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Routes

ConstanciaRoutes.js:6 
router.get('/constanciaView/:constanciaValidacion', 
  ConstanciaController.ConstanciaView)

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Controller

ConstanciaController.js:6-29 Key operations:
  1. Decrypt validation parameter
  2. Query certificate data
  3. Query employee data
  4. Generate QR code
  5. Render view

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Models

ConstanciaModel.js:2-8 SQL queries for retrieving certificate and employee information.

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Integration Example

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Creating a Certificate

While the API doesn’t expose a POST endpoint for certificate creation in the provided code, certificates are likely created during the evaluation completion process: 
import ncrypt from 'ncrypt-js';

// Encrypt evaluation ID
const ncryptObjet = new ncrypt(secretKey);
const encryptedEvalID = ncryptObjet.encrypt(evalID.toString());

// Insert certificate record
await PoolvLife.query(`
  INSERT INTO tbl_dgo_constancias 
  SET evalID = ?, constanciaValidacion = ?, constanciaActivo = 1
`, [evalID, encryptedEvalID]);

// Redirect to certificate view
res.redirect(`/Constancia/constanciaView/${encryptedEvalID}`);

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Displaying Certificate

<!-- In constanciaView.hbs template -->
<div class="certificate">
  <h1>Constancia de Evaluación</h1>
  <p><strong>Nombre:</strong> {{Empleado.empNombreCompleto}}</p>
  <p><strong>RFC:</strong> {{Empleado.empRFC}}</p>
  <p><strong>Fecha:</strong> {{formatDate dataConstancia.constanciaCreado}}</p>
  
  <div class="qr-code">
    <img src="{{QR}}" alt="QR de Validación" />
    <p>Escanee el código QR para validar</p>
  </div>
</div>

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Use Cases

  1. Official Certification: Provide employees with proof of completed background check
  2. Third-Party Verification: Allow employers to verify certificate authenticity
  3. Compliance Documentation: Meet regulatory requirements for background checks
  4. Digital Records: Maintain digital certificates alongside paper copies
  5. Anti-Fraud: Prevent forged or altered certificates through QR validation

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Best Practices

Security
  • Always use HTTPS in production for validation URLs
  • Rotate encryption keys periodically
  • Log validation attempts for audit trail
  • Implement rate limiting on validation endpoint
User Experience
  • Provide clear instructions for QR code scanning
  • Include manual validation option (folio number lookup)
  • Ensure QR code is high-contrast and scannable
  • Test QR codes with multiple scanner apps
Reliability
  • Cache certificate views to reduce database load
  • Handle expired certificates gracefully
  • Implement proper error logging
  • Provide fallback validation methods

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