Pretty Good Privacy (PGP) is an encryption program that provides confidentiality, integrity, and authentication for data communication. PGP operates at the Application layer of the OSI model. This is because it is used to encrypt and decrypt texts, emails, files, directories, and whole disk partitions and to enhance the security of email communications. PGP provides these services by utilizing cryptographic privacy and authentication through a hybrid approach that combines symmetric and asymmetric encryption, which is implemented at the Application layer.
References: The explanation aligns with the functionalities of PGP as described in the context of the OSI model and is consistent with the Certified Network Defender (CND) course material. For further details, please refer to the official CND study guide and documents.