+ V3 keys (pgp 2.6x keys) are deprecated. Not only do they rely on md5 for
+ their fingerprint and signatures, they also use the patented IDEA algorithm
+ for encryption. Also, there are several attacks that make creating new keys
+ with the same keyid trivial. Others make it possible to create different
+ keys with the same fingerprint (tho the key will not actually contain valid
+ RSA parameters).
+
+ Because of these problems a lot of people (like caff's author) refuse to sign
+ v3 keys these days.
+
+ If you still want to sign v3 keys, sign v3 separately. Batch processing does
+ not work. See README.v3-keys.