Open Charge Point Interface OCPI Security Testing and Validation

The Open Charge Point Interface (OCPI) is a protocol standard used for interoperability between electric vehicle charging service providers and roaming partners. OCPI defines how systems exchange data about tariffs, charging availability, session records and billing information. Because OCPI messages often carry sensitive operational, billing and user information and are used between organisations, weaknesses in message handling or session logic can lead to unauthorised access, data manipulation, service disruption or financial loss.

At CyTAL we provide comprehensive protocol aware security testing of OCPI implementations using our ProtoCrawler platform. We assess API message parsing, token and credential handling, session and connection management, data validation, error handling and resilience under abnormal or adversarial conditions. Our goal is to help you identify and remediate vulnerabilities before your OCPI endpoints are deployed in live roaming environments.

What Is the Open Charge Point Interface OCPI

OCPI is a roaming protocol standard that enables organisations to share information about charging services. It supports:

Exchange of tariff and pricing information
Reporting of charging station status and availability
Transmission of session and transaction records
Management of charging locations and footprints
Support for tokens and credentials used in roaming and billing

OCPI is typically used between electric mobility service providers, charge point operators and roaming platforms to enable customers to use charging services across different networks. Correct implementation is essential to ensure data integrity, secure credential exchange and reliable session handling.

Architecture and Attack Surface

OCPI implementations are typically RESTful web API services that communicate over HTTPS. Vulnerabilities may occur in the way messages are parsed, how authentication tokens are validated, how state and session logic is enforced and how backend systems are integrated.

Message Parsing and Field Validation

OCPI messages contain structured JSON data. Potential issues include:

Incorrect parsing of JSON attributes
Missing or improper validation of required fields
Acceptance of unexpected or additional fields without checks
Incorrect handling of null or empty values

Errors in message parsing can lead to logic flaws, incorrect behaviour or crashes.

Token, Credential and Authentication Management

OCPI uses tokens and credentials to authenticate API calls between parties. Weaknesses arise when:

Tokens are accepted without validation
Tokens are reused or predictable
Credentials are stored insecurely
Token expiry or revocation is not enforced

Token and credential weaknesses can allow unauthorised access, session hijack or manipulations of sensitive information.

Session and Connection Handling

OCPI involves session management between roaming partners. Vulnerabilities may occur when:

Connections are accepted without proper verification
Session state is not cleaned up correctly
Reconnection logic is flawed
Multiple concurrent sessions are mishandled

These issues can lead to unstable sessions or unauthorised reuse of stale session state.

Data Validation and Business Logic Enforcement

OCPI implements business logic around sessions, transactions, tariffs and status updates. Weaknesses include:

Acceptance of data outside allowed ranges
Lack of consistency checks between related fields
Inconsistent enforcement of business rules
Incorrect error responses for invalid states

Business logic weaknesses can lead to incorrect billing, displayed availability or transaction records.

Transport and Security Handling

OCPI typically uses HTTPS for security. Vulnerabilities may occur when:

TLS is not enforced correctly
Certificates are accepted without validation
Weak cipher suites are permitted
Transport level errors are not handled safely

Transport layer weaknesses can expose messages to interception or downgrades.

Backend or Integration Layer Issues

OCPI systems often integrate with backend services for billing, logging or analytics. Risks include:

Backend services supplying unvalidated or unsafe data
Protocol logic trusting backend values without verification
Lack of isolation between API logic and backend operations

Integration faults can allow backend errors to affect protocol behaviour.

Common Vulnerabilities in OCPI Implementations

Based on research and testing in roaming and charging service environments, these issues are frequently encountered:

JSON parsing logic that accepts malformed or unexpected data
Weak token or credential enforcement allowing unauthorised access
Session state problems leading to unstable connections or replay
Failure to enforce business rules for transactions or tariffs
Incorrect handling of error responses from partners
Transport layer weaknesses such as lack of strict TLS enforcement
Integration issues where backend supplied values are trusted without validation

Testing OCPI Implementations with ProtoCrawler

ProtoCrawler performs deep, protocol aware testing for OCPI endpoints under normal, abnormal and adversarial conditions.

Structured Message Mutation and Validation

We generate valid OCPI API messages and apply controlled mutations including:

Modified attribute values
Missing required fields
Extra unexpected fields
Corrupted JSON structures

This tests parser robustness and field validation logic.

Token and Credential Handling Tests

ProtoCrawler evaluates authentication handling by:

Sending requests with invalid tokens
Replaying valid tokens
Testing token expiry and revocation behaviour
Using predictable or weak token values

This confirms that the implementation rejects unauthorised requests.

Session and Connection Behaviour Evaluation

We test session handling by:

Repeated connection attempts
Invalid session state transitions
Abrupt disconnects and reconnects
Misordered session sequences

This helps identify unstable session logic and state management faults.

Business Rule and Data Consistency Testing

ProtoCrawler injects:

Out of range data values
Inconsistent related fields
Invalid state transitions in business records

This evaluates whether business logic and data integrity rules are enforced correctly.

Transport and TLS Stress Testing

We assess transport layer behaviour by:

Testing connection attempts with weak TLS settings
Invalid or self signed certificates
Partial or truncated HTTPS exchanges
Transport interruptions

This reveals weaknesses in transport level security handling.

Integration and Backend Fault Simulation

We simulate backend responses that are unexpected or malformed to test whether the OCPI implementation:

Validates backend values before use
Isolates protocol logic from backend faults
Recovers safely from backend errors

This identifies integration related issues.

Stress and Denial of Service Scenarios

We simulate:

High volume API requests
Mixed valid and invalid sequences
Rapid session changes
Repeated malformed messages

This helps identify denial of service risks and resilience issues.

Best Practices for Secure OCPI Deployments

Strict Input Validation

Validate all incoming JSON fields before processing. Reject malformed, unexpected or incomplete data early.

Strong Token and Credential Management

Verify tokens and credentials correctly on every request. Enforce expiry and revocation policies and avoid storing secrets insecurely.

Robust Session and Connection Logic

Clean up session state properly on disconnect. Validate reconnection logic and reject stale session identifiers.

Business Rule Enforcement

Apply consistent checks for data and business logic rules. Validate related fields together and reject inconsistent data sets.

Transport and TLS Hardening

Enforce HTTPS with strict TLS settings. Validate certificates thoroughly and avoid weak cipher suites.

Safe Integration with Backend Systems

Verify backend supplied data before use. Ensure API logic is isolated from backend faults and errors.

Monitoring and Logging

Record API activity, errors and unusual patterns. Use alerts to detect repeated failures or abnormal behaviour.

Frequently Asked Questions About OCPI Security Testing

Q: Why is OCPI security testing important
OCPI enables roaming and data exchange between service providers. Weaknesses in message handling or token logic can lead to unauthorised access, incorrect billing data or service disruption.

Q: Can malformed JSON messages cause incorrect behaviour
Yes. Without strict validation, malformed or unexpected data can lead to incorrect parsing or compromise of business logic.

Q: Is HTTPS enough to secure OCPI
HTTPS is necessary, but correct implementation, certificate validation and transport handling are also required to prevent interception or downgrade.

Q: Does ProtoCrawler support session logic testing for OCPI
Yes. ProtoCrawler can model session sequences and test for invalid or unexpected session behaviour.

Q: How often should OCPI endpoints be tested
At minimum before deployment and after code or configuration changes. For roaming or public deployments regular testing is strongly recommended.

Secure Your OCPI Implementation with CyTAL

OCPI plays a key role in enabling roaming and interoperability across charging networks. CyTAL’s ProtoCrawler platform provides deep, protocol aware testing that uncovers parsing errors, authentication weaknesses, session logic faults, business logic issues and integration vulnerabilities before they impact production systems.

Open Charge Point Interface (OCPI)