OAuth authentication, invalid signature

Question

I tired to port the request-oauth library (based on python-request) to Python 3 (with help of 2to3) but I have problems to validate a signature with StatusNet (same API as Twitter).

When I do a request to oauth/request_token, I have no problem but to oauth/access_token I have an error 401 Invalid signature. I don't understand why because it seems to me that what I sign is correct.

For example, with the python 2 code, cf hook.py and auth.py (original from the git repo), I get :

signing_key = '0de1456373dfc9349dd38a48e61fc844&136d6b9a597ee57d4338254812681acd',
signing_raw = 'POST&http%3A%2F%2Fstatus2.dotzero.me%2Fapi%2Foauth%2Faccess_token&oauth_consumer_key%3Dec3ad931b294b51a5ff595c732acb7a5%26oauth_nonce%3D33448267%26oauth_signature_method%3DHMAC-SHA1%26oauth_timestamp%3D1332279747%26oauth_token%3D2131043f3516bcb730d391ed2033a880%26oauth_verifier%3D8816492%26oauth_version%3D1.0'
oauth_hook.token.key = '2131043f3516bcb730d391ed2033a880'
oauth_hook.token.secret = '136d6b9a597ee57d4338254812681acd'
request.data_and_params = {'oauth_version': '1.0', 'oauth_signature': 'xyjxH5QcfZXnG111L7qANZ+ahRI=',
    'oauth_token': '2131043f3516bcb730d391ed2033a880', 'oauth_nonce': '33448267', 
    'oauth_timestamp': '1332279747', 'oauth_verifier': '8816492', 
    'oauth_consumer_key': 'ec3ad931b294b51a5ff595c732acb7a5', 
    'oauth_signature_method': 'HMAC-SHA1'}

and with my python 3 port, cf hook.py and auth.py, I get :

signing_key = '0de1456373dfc9349dd38a48e61fc844&136d6b9a597ee57d4338254812681acd',
signing_raw = 'POST&http%3A%2F%2Fstatus2.dotzero.me%2Fapi%2Foauth%2Faccess_token&oauth_consumer_key%3Dec3ad931b294b51a5ff595c732acb7a5%26oauth_nonce%3D52360702%26oauth_signature_method%3DHMAC-SHA1%26oauth_timestamp%3D1332278837%26oauth_token%3D2131043f3516bcb730d391ed2033a880%26oauth_verifier%3D8816492%26oauth_verifier%3D8816492%26oauth_version%3D1.0'
oauth_hook.token.key = '2131043f3516bcb730d391ed2033a880'
oauth_hook.token.secret = '136d6b9a597ee57d4338254812681acd'
request.data_and_params = {'oauth_nonce': '52360702', 'oauth_timestamp': '1332278837', 
    'oauth_verifier': '8816492', 'oauth_consumer_key': 'ec3ad931b294b51a5ff595c732acb7a5', 
    'oauth_signature_method': 'HMAC-SHA1', 'oauth_version': '1.0', 
    'oauth_token': '2131043f3516bcb730d391ed2033a880',
    'oauth_signature': 'BRsb11dk++405uaq5pRS+CMUzbo='}

Both looks good to me but the first one succeed and the second returns a 401 error, invalid signature.

In both cases, I get the token.key and token.secret as the result of :

OAuthHook.consumer_key = self.ckey
OAuthHook.consumer_secret = self.csecret
oauth_hook = OAuthHook()
client = requests.session(hooks={'pre_request': oauth_hook})
response = client.post('%soauth/request_token' % (self.url), {'oauth_callback': 'oob'})
# new oauth_hook with the request token
oauth_hook = OAuthHook(response[b'oauth_token'][0],response[b'oauth_token_secret'][0])

Them, I go to oauth/authorize?oauth_token=%s" % oauth_hook.token.key to get authorize the app and get a pincode. After that I can do the problematic request

...
response = client.post('%soauth/request_token' % (self.url), {'oauth_callback': 'oob'})
oauth_hook = OAuthHook(response[b'oauth_token'][0],response[b'oauth_token_secret'][0])
# get the pincode from %soauth/authorize?oauth_token=%s" % (self.url, oauth_hook.token.key)
oauth_hook.token.set_verifier(pincode)
client = requests.session(hooks={'pre_request': oauth_hook})
response = client.post("%soauth/access_token" % (self.url),
                 {'oauth_verifier': pincode})

The signature code from the auth.py file is

def sign(self, request, consumer, token):
    """Builds the base signature string."""
    key, raw = self.signing_base(request, consumer, token)
    hashed = hmac.new(key.encode(), raw.encode(), sha1)
    # Calculate the digest base 64.
    return binascii.b2a_base64(hashed.digest())[:-1]

Any idea why it doesn't work with the py3k code ?

Thank you

Answer 1

Found the answer ! There were two oauth_verifier in the POST request, leading to a wrong signature...

Answer 2

You may need to verify the Authorization header string in your request. Normally it would be of the format:

'Authorization' => 'OAuth realm="",oauth_timestamp="1243392158",oauth_nonce="VsaPHb",oauth_consumer_key="xxxxxxxxxxxxxxxxxx",oauth_token="xxxxxx-xxxx-xxxxxxxxxxxxxx",oauth_version="1.0",oauth_signature_method="HMAC-SHA1",oauth_signature="xxxxxxxxxxxxxxxxxxxx"'

In the above header value, check that the "oauth_signature" is decoded properly. That is, it should not contain values like: %3D. You can use this tool to decode the string.

This has worked for me. Hope it helps someone.