Which layer of the OSI model is responsible for data encryption?

The Presentation Layer of the OSI model is responsible for data encryption. This layer serves as a translator between the application layer and the network, ensuring that data is in a usable format when transmitted across the network or displayed to users. One of its key functions is to format, encrypt, and compress data for the application layer above it.

Encryption is essential for securing sensitive information as it transforms readable data (plaintext) into an unreadable format (ciphertext), making it difficult for unauthorized users to access the information. By handling encryption at the Presentation Layer, the OSI model allows for a clear separation of concerns: the application layer can focus on user interaction while the Presentation Layer ensures that the data is secure and properly formatted for transmission.

In the context of the other layers, the Application Layer primarily deals with user interface and application-level protocols without directly addressing data security. The Transport Layer focuses on end-to-end communication and reliability of data transfer rather than data format or encryption. Lastly, the Network Layer is concerned with routing and forwarding packets across multiple networks, again not involving encryption processes directly. Therefore, the Presentation Layer is the correct answer regarding the responsibility for data encryption within the OSI model.