Lot of refactorings:

    - Added PKCS#1 module
    - Moved some functionality to common.py
    - simplified random number generation
    - improved and extended doctests
    - added changelog

1 files changed, 12 insertions, 24 deletions

diff --git a/rsa/randnum.py b/rsa/randnum.py
index 9bfaded..1129a9b 100644
--- a/rsa/randnum.py
+++ b/rsa/randnum.py
@@ -1,38 +1,26 @@
 '''Functions for generating random numbers.'''
 
-import math
 import os
-import random
 
-import rsa.transform
+from rsa import common, transform
 
 def read_random_int(nbits):
-    """Reads a random integer of approximately nbits bits rounded up to whole
-    bytes
+    """Reads a random integer of approximately nbits bits.
+    
+    The number of bits is rounded down to whole bytes to ensure that the
+    resulting number can be stored in ``nbits`` bits.
     """
 
-    nbytes = int(math.ceil(nbits/8.))
-    randomdata = os.urandom(nbytes)
-    return rsa.transform.bytes2int(randomdata)
+    randomdata = os.urandom(nbits / 8)
+    return transform.bytes2int(randomdata)
+
+def randint(maxvalue):
+    """Returns a random integer x with 1 <= x <= maxvalue"""
 
-def randint(minvalue, maxvalue):
-    """Returns a random integer x with minvalue <= x <= maxvalue"""
 
     # Safety - get a lot of random data even if the range is fairly
     # small
-    min_nbits = 32
-
-    # The range of the random numbers we need to generate
-    range = (maxvalue - minvalue) + 1
+    readbits = max(common.bit_size(maxvalue), 32)
 
-    # Which is this number of bytes
-    rangebytes = (rsa.transform.bit_size(range) + 7) / 8
-
-    # Convert to bits, but make sure it's always at least min_nbits*2
-    rangebits = max(rangebytes * 8, min_nbits * 2)
-    
-    # Take a random number of bits between min_nbits and rangebits
-    nbits = random.randint(min_nbits, rangebits)
-    
-    return (read_random_int(nbits) % range) + minvalue
+    return (read_random_int(readbits) % maxvalue) + 1