On Nov 1, 2:15 pm, Raymond Hettinger <[EMAIL PROTECTED]> wrote:
> On Nov 1, 4:45 am, Aaron Watters <[EMAIL PROTECTED]> wrote:
>
> > Marshal is more secure than pickle
>
> "More" or "less" make little sense in a security context which
> typically is an all or nothing affair. Neither module is designed for
> security. From the docs for marshal:
>
> '''
> Warning: The marshal module is not intended to be secure against
> erroneous or maliciously constructed data. Never unmarshal data
> received from an untrusted or unauthenticated source.
> '''
>
> If security is a focus, then use xmlrpc or some other tool that
> doesn't construct arbitrary code objects.
I disagree. Xmlrpc is insecure if you compile
and execute one of the strings
you get from it. Marshal is similarly insecure if you evaluate a code
object it hands you. If you aren't that dumb, then neither one
is a problem. As far as I'm concerned marshal.load is not any
more insecure than file.read.
Pickle on the other hand can execute just about anything without
you knowing anything about it. It is a horrendous mistake
to suggest that anyone should implement RPC using pickle. If they
want it to be fast they can use marshal, except for that thing
about non-portability which was a design mistake, imho.
By the way: here is a test program which shows pickle running
4 times slower than marshal on my machine using python 2.5.1:
"""
import marshal
import cPickle
import time
def pdump(value, f):
#cPickle.dump(value, f, 2)
return cPickle.dumps(value, 2)
def mdump(value, f):
#marshal.dump(value, f)
return marshal.dumps(value)
def test(dump, fn):
now = time.time()
#f = open(fn, "wb")
f = None
for i in range(3):
D = {}
for j in range(200000):
k = (i*133+j*119)%151
D[ (str(k),str(j)) ] = (str(i), [k, str(k)])
dump(D.items(), f)
#f.close()
elapsed = time.time()-now
print dump, elapsed
if __name__=="__main__":
test(mdump, "mdump.dat")
test(pdump, "ptemp.dat")
"""
-- Aaron Watters
===
If you think you are smart enough to write multi-threaded programs
you're not. -- Jim Ahlstrom's corollary to Murphy's Law.
http://www.xfeedme.com/nucular/pydistro.py/go?FREETEXT=ahlstrom
--
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