GnuPG

GnuPG (GNU Privacy Guard) is a widely used free software encryption system that implements the OpenPGP standard to provide secure communication and data protection across multiple platforms. It uses a hybrid cryptographic approach combining symmetric encryption for performance with public-key cryptography for secure key exchange and identity verification. The software allows users to encrypt files and messages, create digital signatures, and manage cryptographic keys, making it a foundational tool for privacy-focused workflows. Because it is open source and licensed under the GNU GPL, GnuPG can be freely audited, modified, and redistributed, which has contributed to its adoption in security-sensitive environments. It is primarily command-line driven but can be integrated into email clients, messaging tools, and graphical front-ends for broader usability.