What concept restricts one software unit from accessing the private data of another?

The concept that restricts one software unit from accessing the private data of another is best known as data protection or data hiding. This principle is fundamental in software development and security, emphasizing the necessity to conceal the inner workings and private data of software components from other entities or units within the system.

Data hiding ensures that an object's internal state can only be changed through its public methods, which helps preserve the integrity of the internal state and prevents malicious or unintended interference from other parts of the program. This encapsulation not only protects the data but also allows for modular programming practices where units can be developed independently without exposing sensitive data.

While data isolation, access control, and data integrity are also critical security concepts, they serve different purposes. Data isolation typically refers to the separation of data environments to prevent interference or contamination, which is more relevant in instances where different applications or instances need to access data safely. Access control relates to permissions assigned to users for accessing resources, focusing on who can do what, rather than protecting the data itself from other software units. Data integrity ensures that the data remains accurate and uncorrupted over its lifecycle but does not specifically address access restrictions between software units.

Thus, data protection or data hiding is the most appropriate term to describe the