Fix symkey retrieval in python client

Keys (like symmetric keys and asymmetric keys) are returned
from the KRA either encrypted or key wrapped.  Because the
AES keywrapping algorithm cannot be decrypted using AES CBC,
we need special logic to unwrap the keys.

The flow here is as follows:
1. When a key retrieval request is sent to the server,
   the client sends the encryption and key wrapping
   algorithms it requires the key to be wrapped along
   with the wrapping key.
2. If no encryption algorithm or key wrap algorithm is
   recieved, the server assumes its talking to an old
   client and uses DES3.
3. The key is retrieved and (on server's choice) is wrapped
   or encrypted.  The return package will have either
   encryption or key wrap algorithm set (depending on how
   the key was encrypted/wrapped.)
4. client uses that to determine how to unwrap key.

This patch:
1. Makes sure the key wrap algorithm requested by client
   is passed through and used to wrap the retrieved key.
2. Adds logic in the python client to unwrap/decrypt.
3. As python-cryptography does not yet support
   AES KeyWrap with padding, the python client is configured
   to request AES-CBC by default.

Change-Id: I4ba219bade821249b81e4e9a088959c27827ece1

0 files changed, 0 insertions, 0 deletions