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Authentication

The Danish CVR Registry API requires HTTP Basic Authentication for all requests.

Obtaining Credentials

Credentials Required

You must obtain valid credentials from the Danish Business Authority before using the API.

How to Request Access

  1. Email the CVR Support Team: 

    To: cvrselvbetjening@erst.dk
Subject: CVR API Access Request

  2. Include in your request:

  3. Your organization name
  4. Your organization ID (leave out if working as private)
  5. Contact information

  6. Inform if you require access to beneficial owners

  7. Wait for approval - Processing may take up to 3 weeks.

Setting Up Authentication

Store your credentials as environment variables for security:

export CVR_USERNAME="your_username_here"
export CVR_PASSWORD="your_password_here"

$env:CVR_USERNAME = "your_username_here"
$env:CVR_PASSWORD = "your_password_here"

docker run -e CVR_USERNAME="your_username_here" \
           -e CVR_PASSWORD="your_password_here" \
           your-app:latest

Configuration Files

For applications, use configuration files with environment variable substitution:

cvr:
  username: "${CVR_USERNAME}"
  password: "${CVR_PASSWORD}"
  base_url: "http://distribution.virk.dk/cvr-permanent"

{
  "cvr": {
    "username": "${CVR_USERNAME}",
    "password": "${CVR_PASSWORD}",
    "base_url": "http://distribution.virk.dk/cvr-permanent"
  }
}

.env Files

Create a .env file for local development:

# .env file (do not commit to version control)
CVR_USERNAME=your_username_here
CVR_PASSWORD=your_password_here

Add .env to your .gitignore:

echo ".env" >> .gitignore

Testing Authentication

Verify your credentials work correctly:

curl -u "$CVR_USERNAME:$CVR_PASSWORD" \
  -X POST "http://distribution.virk.dk/cvr-permanent/virksomhed/_search" \
  -H 'Content-Type: application/json' \
  -d '{"size": 1}'

Expected Response

A successful authentication returns company data:

{
  "took": 16,
  "timed_out": false,
  "_shards": {
    "total": 6,
    "successful": 6,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 2194982,
    "max_score": 1.0,
    "hits": [
      {
        "_index": "cvr-v-20220630",
        "_type": "_doc",
        "_id": "...",
        "_score": 1.0,
        "_source": {
          "Vrvirksomhed": {
            "cvrNummer": 12345678,
            "navne": [...]
          }
        }
      }
    ]
  }
}

Authentication Errors

HTTP 401 - Unauthorized

<html>
<head><title>401 Authorization Required</title></head>
<body>
<center><h1>401 Authorization Required</h1></center>
<hr><center>nginx</center>
</body>
</html>

Common Causes: - Incorrect username or password - Expired credentials

Solutions: - Verify credentials with CVR support team - Check environment variables are set correctly - Ensure no special characters are causing encoding issues

Security Best Practices

Never Commit Credentials

Never store credentials directly in your code or commit them to version control.

✅ Do This

  • Use environment variables
  • Store in secure credential management systems (AWS Secrets Manager, Azure Key Vault, etc.)
  • Use configuration files with environment variable substitution
  • Implement credential rotation procedures

❌ Don't Do This

  • Hardcode credentials in source code
  • Store credentials in configuration files without environment variables
  • Share credentials via email or chat
  • Use the same credentials across multiple environments

Credential Management in Production

import boto3
import json

def get_cvr_credentials():
    client = boto3.client('secretsmanager', region_name='eu-west-1')
    secret = client.get_secret_value(SecretId='cvr-api-credentials')
    credentials = json.loads(secret['SecretString'])
    return credentials['username'], credentials['password']

from azure.keyvault.secrets import SecretClient
from azure.identity import DefaultAzureCredential

def get_cvr_credentials():
    credential = DefaultAzureCredential()
    client = SecretClient(vault_url="https://your-vault.vault.azure.net/", 
                         credential=credential)

    username = client.get_secret("cvr-username").value
    password = client.get_secret("cvr-password").value
    return username, password

apiVersion: v1
kind: Secret
metadata:
  name: cvr-credentials
type: Opaque
data:
  username: base64_encoded_username
  password: base64_encoded_password

IP Restrictions

Network Access

The CVR API may have IP-based restrictions. Ensure your production systems can access the API endpoint from their network locations.

If you encounter network connectivity issues:

  1. Check if your organization's firewall blocks HTTP (non-HTTPS) traffic
  2. Verify the API endpoint is accessible from your deployment environment
  3. Consider using a proxy or VPN if required by your network policies

Next Steps

Once authentication is working:

  1. Quick Start Guide - Try basic queries
  2. API Reference - Learn about available endpoints
  3. Query Examples - See practical query patterns