Re: RSA exponent

It's likely because OpenSSL (and the M2 wrapper) are returning an MPI -
which has it's length as the first four bytes and remainder being the
number in big-endian byte order.

On Tue, 2004-08-03 at 21:39 +0200, Larry Bugbee wrote:
> I could use some help...
> 
> When I generate a RSA key pair I use 65537 as the exponent.  Later when I go
> to extract the exponent I get 50397185.  In hex it's actually 00 00 00 03 01
> 00 01, but if I discard the 4 high order bytes, 01 00 01 evaluates to 65537.
>  Perhaps you have a suggestion?
> 
> Here is a minimalist version of my code.
> 
> from M2Crypto import RSA
> key = RSA.gen_key(1024, 65537)
> print type(key.e)
> print len(key.e)
> for c in key.e:
>     print ord(c),
> print
> e = 0
> for c in key.e:
> # e = (e << 8) + ord(c)
>  e = (e*256) + ord(c)
> print e
> 
> I get the same results on both MacOSX and Win2000.
>  - OSX 10.3.4, python 2.3, openssl 0.9.7b, M2Crypto 0.13 (with DSA patches)
>  - Win2000, python 2.3.4, openssl 0.9.7b, M2Crypto 0.13 (no patches)
> 
> OpenSSL is not the latest version, but I should be OK.
> 
> Thanks,
> 
> Larry
--

...Dan Berger [[email protected]]
   Department of Computer Science
   Surge Building, Room 357
   University of California, Riverside
   http://www.cs.ucr.edu/~dberger

   "Man had always assumed that he was more intelligent than dolphins
    because he had achieved so much... the wheel, New York, wars, and
    so on, whilst all the dolphins had ever done was muck about in the
    water having a good time. But conversely the dolphins believed
    themselves to be more intelligent than man for precisely the same
    reasons."

        - Douglas Adams, The Hitchhiker's Guide to the Galaxy

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.3 (GNU/Linux)

iD8DBQBBEBTVhHyVxVGhKFYRAuwuAJ448CPk4FTBk87iTx7Hgf5yZVFkmwCgpXMX
rUqj9CqgbuEeAX5l7+WpchA=
=Poz5
-----END PGP SIGNATURE-----