Added hmac-sha1 signature

yubikey.py

@@ -1,15 +1,18 @@
 #!/usr/bin/env python
-
-import requests
 import string
 from random import choice
+import base64
+from hashlib import sha1
+import hmac
+import requests
 
 
 class YubicoWS(object):
     register_ws = 'https://upgrade.yubico.com/getapikey/?format=json'
-    _api_ws = 'http://%s/wsapi/2.0/'
     api_ws = None
-    
+
+    _protocol = 'https'
+
     _servers = [
         'api.yubico.com',
         'api2.yubico.com',
@@ -17,25 +20,37 @@ class YubicoWS(object):
         'api4.yubico.com',
         'api5.yubico.com',
     ]
-    
+    _server = None
+
+    _api_ws = '%s://%s/wsapi/2.0/'
+
     _errors = {
         'BAD_OTP': 'The OTP is invalid format.',
         'REPLAYED_OTP': 'The OTP has already been seen by the service.',
         'BAD_SIGNATURE': 'The HMAC signature verification failed.',
         'MISSING_PARAMETER': 'The request lacks a parameter.',
         'NO_SUCH_CLIENT': 'The request id does not exist.',
-        'OPERATION_NOT_ALLOWED': 'The request id is not allowed to verify OTPs.',
+        'OPERATION_NOT_ALLOWED': 'The request id is not allowed '
-        'BACKEND_ERROR': 'Unexpected error in our server. Please contact us if you see this error.',
+                                 'to verify OTPs.',
-        'NOT_ENOUGH_ANSWERS': 'Server could not get requested number of syncs during before timeout',
+        'BACKEND_ERROR': 'Unexpected error in our server. Please contact '
+                         'us if you see this error.',
+        # 2.0
+        'NOT_ENOUGH_ANSWERS': 'Server could not get requested number of syncs '
+                              'during before timeout',
         'REPLAYED_REQUEST': 'Server has seen the OTP/Nonce combination before',
     }
-    
-    def __init__(self):
-        self.select_random_server()
 
-    def select_random_server(self):
+    def __init__(self, **kwargs):
-        "Select random API Server"
+        self._protocol = kwargs.get('protocol', self._protocol)
-        self.api_ws = self._api_ws % choice(self._servers)
+        self._server = kwargs.get('server', None)
+        self.select_server()
+
+    def select_server(self):
+        "Select server if provided, otherwise uses one from the list"
+        if self._server and self._server in self._servers:
+            self.api_ws = self._api_ws % (self._protocol, self._server)
+        else:
+            self.api_ws = self._api_ws % (self._protocol, choice(self._servers))
 
     def register_api_key(self, email, otp):
         "Registers an API Key with the servers"
@@ -46,57 +61,84 @@ class YubicoWS(object):
         response = requests.post(self.register_ws, data)
         ws_response = response.json()
         if not ws_response['status']:
-            raise WSError(ws_response['error'])
+            raise YubicoWSError(ws_response['error'])
-            
+
         return ws_response
-        
+
     def verify(self, yubikey_id, otp, key=None):
         "Verifies the provided OTP with the server"
         endpoint = 'verify'
         url = self.api_ws + endpoint
-        
+
         # Check otp format
         if not (len(otp) > 32 and len(otp) < 48):
             raise OTPIncorrectFormat()
-            
+
         nonce = self.generate_nonce()
-        
+
         data = {
-            'id': int(yubikey_id),
+            'id': str(yubikey_id),
             'otp': str.lower(otp),
             'nonce': nonce
         }
-        
+
         # Use API key for signing the message if key is provided
         if key:
-            data = self.sign_otp(data, key)
+            data['h'] = self.sign(data, key).replace('+', '%2B')
-        
+
         response = requests.get(url, params=data)
-        
+
         ws_response = self.parse_ws_response(response.text)
-        print(ws_response)
+
         if ws_response['status'] == 'OK':
             # Check if response is valid
             if not (ws_response['nonce'] == nonce \
                 and ws_response['otp'] != otp \
                 and True):
-                raise WSInvalidResponse()
+                raise YubicoWSInvalidResponse()
-            # TODO check signature
+
+            if key:
+                signature = self.sign(ws_response, key)
+
+                if data['h'] != signature:
+                    raise YubicoWSResponseBadSignature(
+                        "The signature sent by the server is invalid"
+                    )
+
         else:
-            raise WSError(self._errors[ws_response['status']])
+            raise YubicoWSError(self._errors[ws_response['status']])
-        
+
         return ws_response
 
-    def sign_otp(self, data, key):
+    def sign(self, data, key):
-        "Signs the OTP with the provided key"
+        "Signs the message with the provided key"
-        return data
+        if 'h' in data:
+            # Just in case
+            data.pop('h')
+
+        # Sorted k=v dict
+        params = []
+        for k in sorted(data.keys()):
+            key_value = "%s=%s" % (k, data[k])
+            params.append(key_value)
+
+        # Join as urlparams
+        string = '&'.join(params)
+
+        # hmac-sha1
+        hashed_string = hmac.new(base64.b64decode(key), string, sha1).digest()
+
+        # base64 encode
+        signature = base64.b64encode(hashed_string)
+
+        return signature
 
     def parse_ws_response(self, text):
         "Parses the API key=value response into a dict"
         data = {}
-        for line in text.strip().split('\n'):
+        for line in text.split():
             key, value = line.split('=', 1)
-            data[key] = value
+            data[key.strip()] = value.strip()
         return data
 
     def generate_nonce(self):
@@ -109,11 +151,11 @@ class Yubikey(object):
     id = None
     key = None
     prefix = None
-    
+
     _last_result = False
-    
+
-    def __init__(self, yubikey_id=None, key=None):
+    def __init__(self, yubikey_id=None, key=None, **kwargs):
-        self.ws = YubicoWS()
+        self.ws = YubicoWS(**kwargs)
         if yubikey_id:
             self.id = yubikey_id
         if key:
@@ -128,36 +170,38 @@ class Yubikey(object):
                 self.id = credentials['id']
                 self.key = credentials['key']
                 result = True
-                
+
         return result
-        
+
     def verify(self, otp):
         "Verify an OTP to check if its valid"
         result = False
         if self.id:
             self.get_prefix(otp)
-            result = self.ws.verify(self.id, otp, key=self.key)
+            try:
-            if result == 'OK':
+                response = self.ws.verify(self.id, otp, key=self.key)
                 result = True
-                
+            except YubicoWSResponseBadSignature, YubicoWSError:
+                result = False
+
         self._last_result = result
         return result
-        
+
     def get_prefix(self, otp):
         "Get prefix from an OTP if present"
         if len(otp) > 32:
             self.prefix = str.lower(otp[:-32])
-        
 
-class WSError(Exception):
+
+class YubicoWSError(Exception):
     def __init__(self, message=None):
         self.msg = "Web Service responded with an error: %s" % message
-    
+
     def __str__(self):
         return repr(self.msg)
-        
 
-class WSInvalidResponse(Exception):
+
+class YubicoWSInvalidResponse(Exception):
     msg = 'Response from the server is invalid'
 
 
@@ -168,3 +212,7 @@ class WSResponseError(Exception):
 
 class OTPIncorrectFormat(Exception):
     pass
+
+
+class YubicoWSResponseBadSignature(Exception):
+    pass