If you use a tool that downloads artifacts from the Central Maven repository, you need to make sure that you are making an effort to validate that these artifacts have a valid PGP signature that can be verified against a public key server. If you don't validate signatures, then you have no guarantee that what you are downloading is the original artifact. One way to to verify signatures on artifacts is to use a repository manager like Nexus Professional. In Nexus Professional you can configure the procurement suite to check every downloaded artifact for a valid PGP signature and validate the signature against a public keyserver.
If you are developing software using Maven, you should generate a PGP signature for your releases. Releasing software with valid signatures means that your customers can verify that a software artifact was generated by the original author and that it hasn't been modified by anyone in transit. Most large OSS forges like the Apache Software Foundation require all projects to be released by a release manager whose key has been signed by other members of the organization, and if you want to synchronize your software artifacts to Maven central you are required to provide pgp signatures.
In this post, I show you how to configure your Maven project to generate a valid signature using GPG. GnuPG ( aka. GPG ) is a freely available implementation of the OpenPGP standard. It's available for both Windows and Unix-like computers. GPG provides you with the capability to generate a signature, manage keys, and verify signatures. In the following sections, I will introduce GPG as well as maven-gpg-plugin which provides Maven goals to generate signatures for a release.