I am used to verify downloaded programs with GnuPG simply by entering the following command:
gpg2 --verify program.exe.sig
Usually, GnuPG finds out which file to hash (in this case program.exe) on its own. But in case of PuTTY, all I got was this:
gpg2 --verify .\putty.exe.DSA
gpg: keine signierten Daten
gpg: can't hash datafile: Keine Daten
However, it is fairly easy to verify the executable, simply by adding the filename to the command line like this:
gpg2 --verify .\putty.exe.DSA <strong>.\putty.exe</strong>
gpg: Signatur vom 07/12/11 21:13:15 Mitteleuropäische Sommerzeit mittels DSA-Schlüssel ID 08B0A90B
gpg: Signatur kann nicht geprüft werden: Kein öffentlicher Schlüssel