Computer Based Testing (CBT) System Upgrade

My existing Computer Based Testing (CBT) system built on PHP and MySQL requires urgent review and upgrades. The enhancements needed are:

1. Power Outage Continuity: Modify the system to allow users to resume their tests from the exact point they were interrupted due to a power outage.

2. Exam Results Management: Implement a feature that can display multiple results for the same user across different examinations.

3. Security Review: Conduct a thorough review of the system's security measures.

Specific Security Enhancements:
- Access Controls: This aspect of the system's security is in most need of improvement. The upgrade should focus on implementing permission levels for different users.

- User Roles: Different permission levels should be assigned primarily to the Student user role. Admin and Teacher roles should remain unaffected.

Ideal Skills and Experience:
- Proficiency in PHP and MySQL
- Extensive experience in system security enhancement
- Previous involvement in CBT system upgrades is a plus
- Ability to implement user role-based permission levels