The security protocols required for integrating the Apollo API with a corporate travel management system include:

1. OAuth 2.0: Implementing OAuth 2.0 for secure authorization and access control.

2. TLS/SSL: Using Transport Layer Security (TLS) or Secure Sockets Layer (SSL) to encrypt data during transmission.

3. API Key Management: Ensuring proper management of API keys and secrets.

4. Data Encryption: Encrypting sensitive data both in transit and at rest.

5. Authentication: Enforcing strong authentication mechanisms to verify user identities.

6. Access Controls: Implementing role-based access controls to limit data access based on user roles.

7. Regular Audits: Conducting regular security audits and vulnerability assessments.

8. Error Handling: Implementing robust error handling to protect against data leaks.

For detailed security guidance, Provab’s API Integration Services can assist.

In summary, key security protocols include OAuth 2.0, TLS/SSL, API key management, data encryption, authentication, access controls, regular audits, and robust error handling.