Pretty Good Privacy (PGP), a widely used program for encrypting and decrypting emails, authenticating messages, and storing encrypted files, has evolved to encompass any encryption software that adheres to the OpenPGP public key cryptography standard. Initially introduced as freeware by Philip R. Zimmermann in 1991, PGP quickly became a popular choice for maintaining privacy and security in email communications, which are often targeted by hackers and malicious actors.
Over the years, the ownership of PGP changed hands multiple times, with companies like PGP Inc., Network Associates Inc. (NAI), Broadcom, Intel, McAfee Associates, Symantec, and Townsend Security all playing a role in marketing and distributing different versions of the software. While the original freeware and commercial versions of PGP are no longer available, the Internet Engineering Task Force (IETF) has published the PGP protocols as Internet standards since 1996. Both open source and commercial implementations of the OpenPGP protocol are widely accessible, with the GNU Privacy Guard (GPG) being a popular choice due to its publication under the GNU Public License (GPL).
Although the Pretty Good Privacy trademark was abandoned in April 2020, the implementation of the OpenPGP specification still commonly refers to itself as PGP. The core functionality of PGP revolves around public-key encryption, where users have an encryption key known publicly and a private key known only to them. This system allows for secure message transmission and digital signatures, enhancing the overall security of email communication. While the original PGP program utilized older algorithms like RSA and Diffie-Hellman, modern implementations now rely on more secure algorithms like AES, AES-256, and 3DES.
The versatility of PGP extends beyond email encryption to include encrypting and digitally signing transmissions in messaging applications, securing disk drives, and providing APIs for developers to integrate PGP functionality into their customized applications. Despite the challenges associated with PGP, such as usability issues and the decentralized infrastructure required for the web of trust, a dedicated user base continues to support the development of OpenPGP-compliant implementations and related applications.
As the history of PGP has unfolded, with key milestones like the publication of the OpenPGP Message Format by the IETF in 2007 and the acquisition of PGP Corp. by Symantec in 2010, the relevance of PGP in the realm of email security remains evident. Despite setbacks like the discovery of the EFAIL bug in 2018 and subsequent ownership changes, PGP continues to be a viable option for individuals and organizations seeking robust encryption solutions for their email communications.