The Bell-LaPadula Model is a formal security model designed to ensure the confidentiality of information by enforcing access controls based on data classification levels and user security clearances and preventing data leakage, but does not address issues like data integrity or availability.

Unlike the Biba model, this model is focused on confidentiality and primarily used for in environments where protecting sensitive information is critical, such as government and military systems.

The model operates on two main principles:

1. Simple Security Property (“no read up”): A subject (user) at a lower security level cannot read data at a higher security level, preventing unauthorized access to sensitive information.
2. Star Security Property (“no write down”): A subject at a higher security level cannot write data to a lower security level, ensuring that sensitive information is not inadvertently leaked to less secure areas.