GPG

An open-source implementation of the OpenPGP standard for encryption and signing.

GPG is a free, open source implementation of the OpenPGP standard used to encrypt and digitally sign data such as files and email. It employs a hybrid scheme, using asymmetric keys to exchange a symmetric session key that encrypts the actual content, balancing security with performance. Trust is established through a decentralized web of trust where users sign each other keys, contrasting with the hierarchical CA structure of PKI. The exam relevance is recognizing GPG as a practical tool for confidentiality, integrity, and nonrepudiation outside a formal certificate authority hierarchy.