silc packet protocol questions

[mailmaus at lewser.de]

hi,

i'm currently trying to learn something about cryptology by diving into
the silc protocol. this might look like a very queer place to start with
but i think it isn't. it's practical.

you got a nice working toolkit. i got the sample code compiled and
running on windows and i also started to have a closer look on the
toolkit itself and on the protocol it implements.

taking one step after another i already stumbled when trying to
understand the SKE protocol. it also uses the silc packet protocol.

and here are the questions.

what is the use of padding in a packet? so far i found out it has
something to do with encryption.
why are packets, that are not encrypted (like the key exchange start
payload) also using it?

thanks in advance
shrew