Signature mismatch, continued - test case

[Adam Langley]

On 8/7/05, Wechsler <wechsler at phase.org> wrote:
> Sorry to keep on with this issue, but I can't track any (used) part of
> my code that fails to meet spec, and I think I've grabbed enough data
> here for others to test.

Ok, I've checked the example over with Python, by hand.

First there's the decoding of the url. Check that you get this
*exactly* (take the SHA1 of it and the string you get from PHP if
possible):
('http', 'phase.home.phase.org', '/openid/response', '',
'originator=wechsler.livejournal.com&openid.mode=id_res&openid.identity=http://wechsler.livejournal.com/&openid.return_to=http://phase.home.phase.org/openid/response?originator=wechsler.livejournal.com&openid.issued=2005-08-07T15:25:54Z&openid.valid_to=2005-08-07T16:25:54Z&openid.assoc_handle=1123428348:Lq2FrMJD6h7JUDue4nrH:0b21753db5&openid.signed=mode,identity,return_to,issued,valid_to&openid.sig=SRJKc2Sp+m28iU/t1jjAe+hct+A=',
'')

>From this you break the arguments apart:
['originator=wechsler.livejournal.com', 'openid.mode=id_res', 
'openid.identity=http://wechsler.livejournal.com/', 
'openid.return_to=http://phase.home.phase.org/openid/response?originator=wechsler.livejournal.com',
'openid.issued=2005-08-07T15:25:54Z', 'openid.valid_to=2005-08-07T16:25:54Z', 
'openid.assoc_handle=1123428348:Lq2FrMJD6h7JUDue4nrH:0b21753db5', 
'openid.signed=mode,identity,return_to,issued,valid_to', 
'openid.sig=SRJKc2Sp+m28iU/t1jjAe+hct+A=']

Check the signed feild and extract those values into the standard
key-value form as defined by the OpenID spec:
c = 'mode:id_res\nidentity:http://wechsler.livejournal.com/\nreturn_to:http://phase.home.phase.org/openid/response?originator=wechsler.livejournal.com\nissued:2005-08-07T15:25:54Z\nvalid_to:2005-08-07T16:25:54Z\n'

Now decode the base64 on the signature
>>> binascii.a2b_base64('SRJKc2Sp+m28iU/t1jjAe+hct+A=')
'I\x12Jsd\xa9\xfam\xbc\x89O\xed\xd68\xc0{\xe8\\\xb7\xe0'
 
in hex, that's:
49124a7364a9fa6dbc894fedd638c07be85cb7e0

Do the same with the MAC key from the assoc operation to get:
351e1d952a23d2d27a2c2b0aea8fe1c522f43adc

Now perform an HMAC_SHA1 with the MAC key above and the key-value data:
>>> import pythistle
>>> h = pythistle.HMAC_SHA1()
>>> h.set_key(binascii.a2b_base64('NR4dlSoj0tJ6LCsK6o/hxSL0Otw='))
>>> h.update(c)
>>> h.digest().encode('hex')
49124a7364a9fa6dbc894fedd638c07be85cb7e0

Check that it matches the signature (it does).

Be happy.


AGL

-- 
Adam Langley                                      agl at imperialviolet.org
http://www.imperialviolet.org                       (+44) (0)7906 332512
PGP: 9113   256A   CC0F   71A6   4C84   5087   CDA5   52DF   2CB6   3D60