Originally Posted by Emerson
Sorry but I've never seen a crazy thing like this associated with Linux kernel. I wouldn't be surprised if this is the root of your issue.
Ah, sorry, you're probably not used to seeing that because it's a bit of a Windows artifact. I downloaded the kernel onto a flash drive under a Windows machine, into a folder named "Linux Kernels." It had a space in it, you see, so I had to use the slash like that as an escape character to get into the directory under Linux.
Anyway, I just found the problem. I evidently needed to unxz it first. This worked:
bash-4.2# unxz linux-3.8.6.tar.xz
bash-4.2# gpg --verify linux-3.8.6.tar.sign
gpg: Signature made Fri 05 Apr 2013 12:49:42 PM EDT using RSA key ID 6092693E
gpg: Good signature from "Greg Kroah-Hartman (Linux kernel stable release signing key) <firstname.lastname@example.org>"
gpg: WARNING: This key is not certified with a trusted signature!
gpg: There is no indication that the signature belongs to the owner.
Primary key fingerprint: 647F 2865 4894 E3BD 4571 99BE 38DB BDC8 6092 693E