This is the package signature as generated by The GnuPG. This signature identifies the party that created the package. By verifying it you are sure that the package coming from a trustworty person or organization.
Here is the package signature:
-----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iEYEABECAAYFAkx4xe4ACgkQqesEzEdeXBG9KwCeM0B63t3tuKYJU+Vm214oJkOe 5SAAoIv/Hy8Vmchldngr4KfBkzij6Zk4 =x//t -----END PGP SIGNATURE-----
You can save this signature in a text file (e.g. gmp-4.3.2-i486-1gds.txz.asc) in the same directory where the package file (gmp-4.3.2-i486-1gds.txz) resides and you can verify it by issuing the following command:
gpg --verify gmp-4.3.2-i486-1gds.txz.asc
NOTE: You need to import the public key of SlackPack first:
gpg --import KEY