[Yum] gpg keys

[Peter M. Abraham]

Greetings:

On a test server, I tried to have yum update zlib-devel, and ran into the 
problem below.

	yum update zlib-devel
	Gathering package information from servers
	Getting headers from: Red Hat Linux 7.3 base
	Getting headers from: Fedora Legacy tools for Red Hat Linux 7.3
	Getting headers from: Red Hat Linux 7.3 updates
	Finding updated packages
	Downloading needed headers
	Resolving dependencies
	.Dependencies resolved
	I will do the following:
	[update: zlib-devel.i386]
	I will install/upgrade these to satisfy the dependencies:
	[deps: zlib.i386]
	Is this ok [y/N]: y
	Getting zlib-devel-1.1.4-8.7x.i386.rpm
	Error: GPG Signature check failed for 
/var/cache/yum/updates/packages/zlib-devel-1.1.4-8.7x.i386.rpm
	You may want to run yum clean or remove the file:
	 /var/cache/yum/updates/packages/zlib-devel-1.1.4-8.7x.i386.rpm
	You may also want to check to make sure you have the right gpg keys
	Exiting.

How do I verify we have the right gpg keys?

And if I have the wrong keys, how do I get the right keys?

Thank you.