Seems to be you got wrong kernel source.
You have to find mirror with "linux-2.6.22.19.tar.bz2.sign" file and check signature like it described at kernel.org
Unfortunately, googlecode don't support subfolders in downloads area, so kernel archive will be mixed in one long list with firmware images As workaround we can upload it with "deprecated" label, but IMHO it is bad solution too...