Gnu Privacy Guard (GnuPG) is an Open Source implementation of the Pretty Good (.html)
Privacy (OpenPGP) specification. Its main purposes are digital authentication,
signature and encryption.
It is often used by the FLOSS community to verify:
To quote Phil Pennock (the author of the SKS key server - http://sks.spodhuis.org/):
You MUST understand that presence of data in the keyserver (pools) in no way connotes trust. Anyone can generate a key, with any name or email address, and upload it. All security and trust comes from evaluating security at the “object level”, via PGP Web-Of-Trust signatures. This keyserver makes it possible to retrieve keys, looking them up via various indices, but the collection of keys in this public pool is KNOWN to contain malicious and fraudulent keys. It is the common expectation of server operators that users understand this and use software which, like all known common OpenPGP implementations, evaluates trust accordingly. This expectation is so common that it is not normally explicitly stated.
Trust can be gained by having your key signed by other people (and signing their key back, too :) ), for instance during key signing parties, see:
$ gpg --gen-key gpg (GnuPG) 2.1.6; Copyright (C) 2015 Free Software Foundation, Inc. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Note: Use "gpg2 --full-gen-key" for a full featured key generation dialog. GnuPG needs to construct a user ID to identify your key. Real name: Marvin the Paranoid Android Email address: firstname.lastname@example.org You selected this USER-ID: "Marvin the Paranoid Android <email@example.com>" Change (N)ame, (E)mail, or (O)kay/(Q)uit? o We need to generate a lot of random bytes. It is a good idea to perform some other action (type on the keyboard, move the mouse, utilize the disks) during the prime generation; this gives the random number generator a better chance to gain enough entropy.
At this point, you will:
gpg: key A9D53A3E marked as ultimately trusted public and secret key created and signed. gpg: checking the trustdb gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model gpg: depth: 0 valid: 2 signed: 0 trust: 0-, 0q, 0n, 0m, 0f, 2u pub rsa2048/A9D53A3E 2015-07-31 Key fingerprint = AF2A 5381 E54B 2FD2 14C4 A9A3 0E35 ACA4 A9D5 3A3E uid [ultimate] Marvin the Paranoid Android <firstname.lastname@example.org>(.html) sub rsa2048/8C0EACF1 2015-07-31
$ gpg --keyserver pgp.mit.edu --send-keys A9D53A3E gpg: sending key A9D53A3E to hkp server pgp.mit.edu
See Release Shaarli.