GNU Privacy Guard
complete implementation of the OpenPGP and S/MIME standards
GNU Privacy Guard (GnuPG or GPG) is a free-software replacement for Symantec's cryptographic software suite PGP. The software is compliant with the now obsoleted RFC 4880, the IETF standards-track specification of OpenPGP. Modern versions of PGP are interoperable with GnuPG and other OpenPGP v4-compliant systems.
November 2023 saw two drafts aiming to update the 2007 OpenPGP v4 specification (RFC4880), ultimately resulting in the RFC 9580 standard in July 2024. The proposal from the GnuPG developers, which is called LibrePGP, was not taken up by the OpenPGP Working Group and future versions of GnuPG will not support the current version of OpenPGP.
GnuPG is part of the GNU Project and received major funding from the German government in 1999.
Overview
GnuPG is a hybrid-encryption software program because it uses a combination of conventional symmetric-key cryptography for speed, and public-key cryptography for ease of secure key exchange, typically by using the recipient's public key to encrypt a session key which is used only once. This mode of operation is part of the OpenPGP standard and has been part of PGP from its first version.
The GnuPG 1.x series uses an integrated cryptographic library, while the GnuPG 2.x series replaces this with Libgcrypt.
GnuPG encrypts messages using asymmetric key pairs individually generated by GnuPG users. The resulting public keys may be exchanged with other users in a variety of ways, such as Internet key servers. They must always be exchanged carefully to prevent identity spoofing by corrupting public key ↔ "owner" identity correspondences. It is also possible to add a cryptographic digital signature to a message, so the message integrity and sender can be verified, if a particular correspondence relied upon has not been corrupted.
The public source identifies “GNU Privacy Guard” as complete implementation of the OpenPGP and S/MIME standards. This brief keeps that definition visible, then builds a research path around Privacy, Guard and complete.
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Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Aug 26, 2026. The linked authority identifier is Q223204. 3 of 4 selected statements include explicit references; 2 carry qualifiers and 2 use preferred rank. The first chronological checks are 2023, 2007, 2024 and 1999.
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This entry incorporates text from “GNU Privacy Guard” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.