irmd: Specify peer authentication contract

OAP accepted requests and responses without a certificate even when
the peer was expected to authenticate. An on-path attacker could
strip the certificate and signature from a flow allocation response
and substitute its own key exchange, silently downgrading the
handshake to unauthenticated.

Add an auth=required|optional policy to enc.conf, enforced per role: a
client config requires the server to present a valid certificate, a
server config requires the same from the client. Default is required
for client side (https), optional server side. The client side default
can be changed via OAP_CLIENT_AUTH_DEFAULT for testing.

Replace the bare 'none' keyword with encryption=none, which disables
encryption only: the digest and the authentication policy are kept, so
authenticated but unencrypted flows can be configured. Configs using
bare 'none' are now rejected.

Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>

1 files changed, 2 insertions, 0 deletions

diff --git a/cmake/config/irmd.cmake b/cmake/config/irmd.cmake
index 45d9e73d..72463458 100644
--- a/cmake/config/irmd.cmake
+++ b/cmake/config/irmd.cmake
@@ -20,6 +20,8 @@ set(FLOW_ALLOC_TIMEOUT 20000 CACHE STRING
 # OAP (Ouroboros Authentication Protocol)
 set(OAP_REPLAY_TIMER 20 CACHE STRING
   "OAP replay protection window (s)")
+set(OAP_CLIENT_AUTH_DEFAULT TRUE CACHE BOOL
+  "Client requires the server to authenticate by default (FALSE for testing)")
 set(DEBUG_PROTO_OAP FALSE CACHE BOOL
   "Add Flow allocation protocol message output to IRMd debug logging")