ezPyCrypto keys

[John Hunter]

I have been playing around with ezPyCrypto. I generated and printed a
key with

import ezPyCrypto
k = ezPyCrypto.key(2048)
print k.exportKey()
I noticed there were a lot of N's and M's, too many to occur by chance

s=k.exportKeyPrivate() s.count('N')/float(len(s)) 0.09788189987163029 s.count('M')/float(len(s))

0.11

I quit python and restarted it and generated a new key and found the
same thing. Ditto when I exported the private key. I also found the
keys generated in the two sessions to be quite similar (35% characters
at a given position identical).

What's going on? Is it abnormal for so many of the characters in the
exported string to be the same? The machine I am running on is a
server that rarely has anyone logged in directly. Is this a problem
with not enough randomness in /dev/random?

Thanks for any suggestions,
John Hunter

ezPyCrypto-0.1.1
pycrypto-1.9a6
python2.2
mother:/var/tmp/ezPyCrypto-0.1.1> uname -a
Linux mother.paradise.lost 2.4.9 #7 Fri Oct 12 15:20:49 CDT 2001 i686
unknown

[Robert Kern]

In article <ma*********************************@python.org> ,
John Hunter <jd******@ace.bsd.uchicago.edu> writes:

[snip]

What's going on? Is it abnormal for so many of the characters in the
exported string to be the same? The machine I am running on is a
server that rarely has anyone logged in directly. Is this a problem
with not enough randomness in /dev/random?
As Heiko suggests, it's just the serialization protocol that is creating
this effect. ezPyCrypto keeps the key as a Python long, pickles it along
with other information, then base64-encodes the resulting string. The
pickled representation of a long doesn't contain the raw bytes; it
contains the string representation, so the pickle contains a lot of
decimal digits rather than a full 0-255 range of bytes. Naturally, this
representation has redundancy which is made more apparent by the
base64-encoding.

All 2048 bits of entropy should still be there.
Thanks for any suggestions,
John Hunter

--
Robert Kern
ke**@caltech.edu

"In the fields of hell where the grass grows high
Are the graves of dreams allowed to die."
-- Richard Harter