From a55991055ef16cb621e160d89bade402bb8de1e2 Mon Sep 17 00:00:00 2001
From: Jakub Warmuz <jakub@warmuz.org>
Date: Sat, 25 Jul 2015 18:17:53 +0000
Subject: [PATCH] Human meaningful exception message for decoding fields with
 minimum length.

---
 acme/acme/jose/json_util.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/acme/acme/jose/json_util.py b/acme/acme/jose/json_util.py
index 0608d3906..51d55ebd9 100644
--- a/acme/acme/jose/json_util.py
+++ b/acme/acme/jose/json_util.py
@@ -326,7 +326,8 @@ def decode_b64jose(data, size=None, minimum=False):
 
     if size is not None and ((not minimum and len(decoded) != size)
                              or (minimum and len(decoded) < size)):
-        raise errors.DeserializationError()
+        raise errors.DeserializationError(
+            "Expected at least or exactly {0} bytes".format(size))
 
     return decoded