Authentication overview

Transport for Czech Republic, specifically the Pražská integrovaná doprava (PID) system, provides access to its public transport data and APIs through an API key authentication model. This approach grants developers and applications access to various data feeds, including GTFS (General Transit Feed Specification) and GTFS-RT (Realtime), as well as dedicated API endpoints for departures, stops, and connections. The API key serves as a unique identifier and secret token that verifies the identity of the requesting application or user, thereby controlling access to the data resources.

The primary purpose of requiring authentication is to manage access, monitor usage, and ensure the stability and availability of the public transport data services. While PID offers generous free access for most standard use cases, the API key mechanism allows for tracking consumption and implementing custom agreements for high-volume or commercial integrations, as detailed in the PID data and API documentation. All API interactions requiring an API key must occur over HTTPS to protect the key and data in transit, adhering to standard web security practices for API communication.

Supported authentication methods

The Transport for Czech Republic (PID) API platform primarily supports API key authentication. This method is a common and straightforward way to secure access to web services by requiring a unique, secret key to be included with each request. The key identifies the client making the request and determines their authorization to access specific resources.

API Key Authentication

  • Method Description: An API key is a simple token that is sent with each API request, typically in a query parameter or a custom HTTP header. It functions as both an identifier and a secret token for the calling application.
  • Purpose: To control access to the PID data feeds and API endpoints, differentiate between consumers, and enforce usage policies.
  • Security Considerations: API keys are generally less secure than token-based systems like OAuth 2.0 for user authorization, but they are effective for application-level authentication. They must be kept confidential and transmitted only over secure channels (HTTPS).

While API Key authentication is the standard for accessing PID data, it's essential to understand its role. API keys are suitable for identifying the application making the request, not necessarily an individual user. For scenarios requiring user-specific authorization, a system might integrate the PID API key with an internal user management system or an OAuth 2.0 flow for its own end-users. However, for direct access to PID data, the API key is the designated method.

The Internet Engineering Task Force (IETF) defines various security considerations for API keys, noting their utility for simple access control but also highlighting the need for careful management to prevent unauthorized usage, as explained in RFC 6749, The OAuth 2.0 Authorization Framework, which contrasts with simpler API key mechanisms.

Authentication Methods Table

Method When to use Security Level
API Key Accessing PID GTFS/GTFS-RT feeds and API endpoints for application-level authentication. Moderate (requires secure handling and transmission over HTTPS)

Getting your credentials

To obtain an API key for Transport for Czech Republic's PID data and APIs, you typically follow a specific registration process through the official PID channels. The process is designed to be straightforward and provides access for most developers and applications under a generous free tier.

  1. Visit the PID Integration & Digitalization Page: Navigate to the PID data and API section on the official PID website. This page serves as the central hub for developers.
  2. Locate the API Key Request Information: Look for sections related to API key requests, access to data feeds, or developer registration. The documentation will outline the specific steps.
  3. Complete the Request Form: You will likely need to fill out a form providing details about your intended use case, contact information, and potentially the name of your application. This helps PID understand how their data will be utilized and allows them to communicate any updates.
  4. Submit and Await Approval: After submitting your request, it will undergo a review process. Once approved, your API key will be provided to you, often via email or through a dedicated developer portal.
  5. Review Usage Terms: Before integrating, carefully read the terms of service and any usage policies associated with the API key. This includes information on rate limits, data redistribution policies, and commercial use. For high-volume or commercial applications, a custom agreement may be necessary, as noted in the PID pricing summary.

It is crucial to treat your API key as a sensitive credential. Do not embed it directly in client-side code, commit it to public repositories, or share it unnecessarily. Secure storage and transmission are paramount to prevent unauthorized access to the PID data.

Authenticated request example

Once you have obtained your API key, you can use it to make authenticated requests to the Transport for Czech Republic (PID) APIs. The specific method for including the API key may vary slightly depending on the API endpoint, but it is commonly passed as a query parameter or an HTTP header.

Example: Including API Key as a Query Parameter

Many RESTful APIs expect the API key to be appended to the URL as a query parameter. Assume your API key is YOUR_API_KEY_HERE and you are accessing an endpoint for real-time departures.

GET /api/v1/departures?stopId=U208Z101&apiKey=YOUR_API_KEY_HERE HTTP/1.1
Host: api.pid.cz
User-Agent: YourAppName/1.0

In this example:

  • api.pid.cz is the hypothetical base URL for the PID API.
  • /api/v1/departures is the specific endpoint being called.
  • stopId=U208Z101 is a hypothetical parameter for a specific stop.
  • apiKey=YOUR_API_KEY_HERE is where your unique API key is provided as a query parameter.

Example: Including API Key as an HTTP Header

Alternatively, some APIs prefer or require the API key to be sent in a custom HTTP header, such as X-API-Key or Authorization (though for simple API keys, Authorization is less common unless combined with schemes like Bearer). Check the PID API reference for the exact header name if this method is supported.

GET /api/v1/connections HTTP/1.1
Host: api.pid.cz
X-API-Key: YOUR_API_KEY_HERE
User-Agent: YourAppName/1.0

In this header-based example:

  • X-API-Key: YOUR_API_KEY_HERE is the custom header containing your API key.

Always refer to the official Transport for Czech Republic API documentation for the most accurate and up-to-date instructions on how to include your API key in requests, as endpoint paths and parameter names can change.

Security best practices

Securing your API keys and ensuring the integrity of your interactions with Transport for Czech Republic's PID APIs is crucial. Following these best practices helps protect your application and the public data it consumes:

  1. Keep API Keys Confidential: Your API key is a secret credential. Never hardcode it directly into client-side code (e.g., JavaScript in a web browser or mobile app distributed to users) where it can be easily extracted. Instead, use server-side components to make API calls, passing the key securely from your server.
  2. Use Environment Variables: Store API keys in environment variables on your server or in secure configuration files, rather than directly in your source code. This prevents accidental exposure in version control systems like Git. Services like Google Cloud's Secret Manager or AWS Secrets Manager offer robust solutions for managing secrets.
  3. Restrict API Key Privileges: While PID API keys generally grant access to public transport data, avoid using a single key for multiple, unrelated applications if possible. If the PID system offers granular permissions (though often not the case for simple API keys), apply the principle of least privilege.
  4. Transmit Over HTTPS Only: Always ensure that all requests to the PID APIs are made over HTTPS (HTTP Secure). HTTPS encrypts the communication channel, protecting your API key and any data exchanged from interception during transit. Unencrypted HTTP requests will likely fail or expose your key.
  5. Implement Rate Limiting and Monitoring: Monitor your API key's usage for unusual patterns or spikes that could indicate unauthorized use. Implement rate limiting in your application to prevent abuse and adhere to any limits imposed by the PID API.
  6. Rotate API Keys Periodically: While not always explicitly required by PID, periodically rotating your API keys (generating a new one and revoking the old one) is a good security practice. This minimizes the impact if a key is compromised.
  7. Avoid Public Repositories: Never commit API keys or configuration files containing them to public code repositories (e.g., GitHub). Use .gitignore or similar mechanisms to exclude these files from your version control.
  8. Validate and Sanitize Inputs: When constructing API requests, always validate and sanitize any user-supplied inputs to prevent injection attacks or malformed requests that could lead to unexpected behavior or security vulnerabilities.
  9. Error Handling: Implement robust error handling in your application. Avoid logging API keys in plain text in application logs, especially if those logs are accessible. Mask or redact sensitive information.

By adhering to these security best practices, developers can significantly reduce the risk of API key compromise and ensure a secure integration with the Transport for Czech Republic's data services.