[minion-cvs] Fix longstanding, obscure, and probably harmless bug in...

[nickm@seul.org (Nick Mathewson)]

Update of /home/minion/cvsroot/src/minion/lib/mixminion
In directory moria.mit.edu:/tmp/cvs-serv23310/lib/mixminion

Modified Files:
	Crypto.py 
Log Message:
Fix longstanding, obscure, and probably harmless bug in RNG.getInt().

(This bug was noticed when I tried to adapt the logic for Tor, and
realized that the logic was wrong.)



Index: Crypto.py
===================================================================
RCS file: /home/minion/cvsroot/src/minion/lib/mixminion/Crypto.py,v
retrieving revision 1.54
retrieving revision 1.55
diff -u -d -r1.54 -r1.55
--- Crypto.py	25 Aug 2003 21:05:34 -0000	1.54
+++ Crypto.py	12 Nov 2003 04:35:14 -0000	1.55
@@ -568,6 +568,7 @@
 
         assert 0 < max < 0x3fffffff
         _ord = ord
+        cutoff = 0x7fffffff - (0x7fffffff % max)
         while 1:
             # Get a random positive int between 0 and 0x7fffffff.
             b = self.getBytes(4)
@@ -577,7 +578,7 @@
                        _ord(b[3]))
             # Retry if we got a value that would fall in an incomplete
             # run of 'max' elements.
-            if 0x7fffffff - max >= o:
+            if o < cutoff:
                 return o % max
 
     def getNormal(self, m, s):