The new code supports reading and writing UPG files. I kept the old keysig
search code but it only supports the old format (the new format has too long
keys anyway). Since we now have to support two types of encryption(DES and AES),
I reorganized the crypto routines and clean-up some code.
Change-Id: Ie9be220ec2431ec6d0bd11699fa0493b62e1cec2