Reinstated some of the backed out changeset 812d745b6bef:

    - added support for block size
    - improved some exceptions

1 files changed, 5 insertions, 2 deletions

diff --git a/rsa/core.py b/rsa/core.py
index 8f989df..2df4be5 100755
--- a/rsa/core.py
+++ b/rsa/core.py
@@ -17,8 +17,11 @@ def encrypt_int(message, ekey, n):
     if not type(message) is types.LongType:
         raise TypeError("You must pass a long or int")
 
-    if message < 0 or message > n:
-        raise OverflowError("The message is too long")
+    if message < 0:
+        raise ValueError('Only non-negative numbers are supported')
+         
+    if message > n:
+        raise OverflowError("The message %i is too long for n=%i" % (message, n))
 
     #Note: Bit exponents start at zero (bit counts start at 1) this is correct
     safebit = rsa.common.bit_size(n) - 2        # compute safe bit (MSB - 1)