Python3 - coinbase API authentication - python-3.6

Question

I am trying to access my coinbase account using their API.
I am using the following code: (which is from the website https://developers.coinbase.com/docs/wallet/api-key-authentication)
import json, hmac, hashlib, time, requests
from requests.auth import AuthBase
# Before implementation, set environmental variables with the names API_KEY and API_SECRET
API_KEY = 'API_KEY'
API_SECRET = 'API_SECRET'
# Create custom authentication for Coinbase API
class CoinbaseWalletAuth(AuthBase):
def __init__(self, api_key, secret_key):
self.api_key = api_key
self.secret_key = secret_key
def __call__(self, request):
timestamp = str(int(time.time()))
message = timestamp + request.method + request.path_url + (request.body or '')
signature = hmac.new(self.secret_key, message, hashlib.sha256).hexdigest()
request.headers.update({
'CB-ACCESS-SIGN': signature,
'CB-ACCESS-TIMESTAMP': timestamp,
'CB-ACCESS-KEY': self.api_key,
})
return request
api_url = 'https://api.coinbase.com/v2/'
auth = CoinbaseWalletAuth(API_KEY, API_SECRET)
# Get current user
r = requests.get(api_url + 'user', auth=auth)
print r.json()
# {u'data': {u'username': None, u'resource': u'user', u'name': u'User'...
However I am getting the following error:
Traceback (most recent call last):
File "test1.py", line 44, in <module>
r = requests.get(api_url + 'user', auth=auth)
File "C:\Users\lclar\virtualenv-env\lib\site-packages\requests\api.py", line 72, in get
return request('get', url, params=params, **kwargs)
File "C:\Users\lclar\virtualenv-env\lib\site-packages\requests\api.py", line 58, in request
return session.request(method=method, url=url, **kwargs)
File "C:\Users\lclar\virtualenv-env\lib\site-packages\requests\sessions.py", line 494, in request
prep = self.prepare_request(req)
File "C:\Users\lclar\virtualenv-env\lib\site-packages\requests\sessions.py", line 437, in prepare_request
hooks=merge_hooks(request.hooks, self.hooks),
File "C:\Users\lclar\virtualenv-env\lib\site-packages\requests\models.py", line 309, in prepare
self.prepare_auth(auth, url)
File "C:\Users\lclar\virtualenv-env\lib\site-packages\requests\models.py", line 540, in prepare_auth
r = auth(self)
File "test1.py", line 29, in __call__
signature = hmac.new(self.secret_key, message, hashlib.sha256).encode("utf-8").digest()
File "C:\Users\lclar\AppData\Local\Programs\Python\Python36-32\lib\hmac.py", line 144, in new
return HMAC(key, msg, digestmod)
File "C:\Users\lclar\AppData\Local\Programs\Python\Python36-32\lib\hmac.py", line 42, in __init__
raise TypeError("key: expected bytes or bytearray, but got %r" % type(key).__name__)
TypeError: key: expected bytes or bytearray, but got 'str'
Can someone please help me?
Thanks in advance.

Answer 1

I assuming the data type self.secret_key = secret_key is a string. For Python >= 3.4, hmac.new(key, msg=None, digestmod=''), the key must be of type bytes or bytearray per the docs: https://docs.python.org/3/library/hmac.html
Likewise to avoid the TypeError: Unicode-objects must be encoded before hashing error, do the same for the message variable as shown below:
signature = hmac.new(self.secret_key.encode(), message.encode(), hashlib.sha256).hexdigest()