Updated README.md

Author: rohe

README.md

@@ -1,2 +1,20 @@
 # oidcmsg
-Implementation of OIDC protocol messages
+Implementation of OIDC protocol messages.
+
+oidcmsg is the 2nd layer in the
+JwtConnect stack (cryptojwt, oidcmsg, oidcservice, oidcrp)
+
+Handles serialising into a couple of formats (jwt, json, urlencoded and dict) and deserialising from said formats.
+
+It also does verification of messages , that is :
+
++ does all the required parameters have a value
++ are the parameter values of the right type
++ if there is a list of permitted values is a parameter value in that list.
+
+Also implements a **KeyJar** which keeps keys belonging to 
+different owners. One owner may have many keys.
+If some of these keys have a common origin, like described in a JWKS.
+Such a set will be kept in a **keyBundle**.
+Also implemented in this package. 
+