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What are the main differences between PGP (Pretty Good Privacy) and GPG (GNU Privacy Guard) in relationship with security in Ubuntu and Launchpad?

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up vote 78 down vote accepted

PGP can refer to two things:

  1. The Pretty Good Privacy software originally written by Phil Zimmermann, and now owned by Symantec.
  2. The formats for keys, encrypted messages and message signatures defined by that software. These have now been formalised as the OpenPGP standard.

The GPG software is an independent implementation of the OpenPGP standards, so you can use it to exchange encrypted messages with people using other OpenPGP implementations (e.g. Symantec's PGP).

Due to its popularity on Linux systems, it is also fairly common for people to incorrectly use the term "GPG" to refer to the whole OpenPGP cryptography system (e.g. "GPG keys" or "GPG signatures"). It is usually pretty clear what they mean from the context though.

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“PGP” stands for “Pretty Good Privacy.” It was developed by Phil Zimmermann. At first it was written as copyrighted freeware under the Gnu Public License. Later, PGP was upgraded and made into a propriety program. The rights for this program are traded around. The reason for this upgrade was legal defense costs and royalty issues related to the export laws of the USA. Now the PGP program is owned by PGP Corporation.

Only the command line version is not owned by PGP Corporation which is also not for sale. PGP uses the RSA algorithm and the IDEA encryption algorithm. The PGP is considered to have Windows interface which is more polished

“GPG” stands for “Gnu Privacy Guard.” GPG is a re-write or upgrade of PGP. It does not use the IDEA encryption algorithm. This is to make it completely free. It uses the NIST AES, Advanced Encryption Standard. All the algorithm data is stored and documented publicly by OpenPGP Alliance. The main reason for this change is that AES costs less than IDEA and is considered more secure. Moreover, it is royalty free because it is not patented. GPG is more compatible than the original PGP with OpenPGP. GPG is also based on a command line. Windows frontends are also available for GPG other than the command line.

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Are you sure the original version was GPL? The Wikipedia article just says that "No license was required for its non-commercial use". – Keith Thompson Sep 12 '12 at 10:05
I'm pretty sure it wasn't ever GPL: if it was, there wouldn't have been a need for GPG to be a clean room implementation. – James Henstridge Oct 3 '12 at 10:33

Gnu Privacy Guard and Pretty Good Privacy -- also referred to as GPG and PGP, respectively -- are data encryption and decryption solutions used for transferring and storing information securely. GPG and PGP are nearly identical, with the major difference between them being how they are licensed to the public.

Read more: The Difference Between GPG and PGP |

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