Human message regarding minimum client_secret length

Author: peppelinux

src/cryptojwt/jwk/hmac.py

@@ -57,7 +57,8 @@ def __init__(
             self.key = b64d(bytes(self.k))
 
         if len(self.key) < 16:
-            raise UnsupportedAlgorithm("key too short")
+            raise UnsupportedAlgorithm("client_secret too short,"
+                                       " it should be at least 16 digits")
 
     def deserialize(self):
         self.key = b64d(bytes(self.k))