The default key is a DSA primary key with an ElGamal key used for
encryption (but this one has the id 20 and not 16 - so it MAY be used
for signatures). Never mind, I#ll put 16 into the encrypted packets
even for keys which have 20 as algorithm identifier.
This won't work with PGP 5.X. It uses the algorithm identifier in the key
packet to determine what kind of key it is. It also uses a combination
of the key id and the alg id internally to index keys, so changing the
alg id in the ESK packet will prevent it from finding your keys.
Hal