GDAX / Coinbase API authentication process: Unicode-objects must be encoded before hashing

Question

I have a lot of experience coding, but Python is new territory for me.

I'm using the CoinbaseExchangeAuth class to access the private endpoints of the GDAX API. I write some simple code...

api_url = 'https://public.sandbox.gdax.com/'
auth = CoinbaseExchangeAuth(API_KEY, API_SECRET, API_PASS)

(note that I have accurately defined the api key, secret and pass correctly before these lines of code - for the sandbox)

Then I write:

r = requests.get(api_url + 'accounts', auth=auth)

Run the code and get this error:

File "a:\PythonCryptoBot\Bot1.0\CoinbaseExhangeAuth.py", line 16, in call signature = hmac.new(hmackey, message, hashlib.sha256) File "C:\Users\Dylan\AppData\Local\Programs\Python\Python35-32\lib\hmac.py", line 144, in new return HMAC(key, msg, digestmod) File "C:\Users\Dylan\AppData\Local\Programs\Python\Python35-32\lib\hmac.py", line 84, in __init_ self.update(msg) File "C:\Users\Dylan\AppData\Local\Programs\Python\Python35-32\lib\hmac.py", line 93, in update self.inner.update(msg) TypeError: Unicode-objects must be encoded before hashing

Also note that I have tried to API_KEY.encode('utf-8') and same with others. - doesn't seem to do anything.

Sectorial

Answer 1

The code you're using is written for Python2, you can't expect it to run as it is. I've modified some parts to make it Python3 compatible.

Original code:

import json, hmac, hashlib, time, requests, base64
from requests.auth import AuthBase

# Create custom authentication for Exchange
class CoinbaseExchangeAuth(AuthBase):
    def __init__(self, api_key, secret_key, passphrase):
        self.api_key = api_key
        self.secret_key = secret_key
        self.passphrase = passphrase

    def __call__(self, request):
        timestamp = str(time.time())
        message = timestamp + request.method + request.path_url + (request.body or '')
        hmac_key = base64.b64decode(self.secret_key)
        signature = hmac.new(hmac_key, message, hashlib.sha256)
        signature_b64 = signature.digest().encode('base64').rstrip('\n')

        request.headers.update({
            'CB-ACCESS-SIGN': signature_b64,
            'CB-ACCESS-TIMESTAMP': timestamp,
            'CB-ACCESS-KEY': self.api_key,
            'CB-ACCESS-PASSPHRASE': self.passphrase,
            'Content-Type': 'application/json'
        })
        return request

api_url = 'https://api.gdax.com/'
auth = CoinbaseExchangeAuth(API_KEY, API_SECRET, API_PASS)

# Get accounts
r = requests.get(api_url + 'accounts', auth=auth)
print r.json()
# [{"id": "a1b2c3d4", "balance":...

# Place an order
order = {
    'size': 1.0,
    'price': 1.0,
    'side': 'buy',
    'product_id': 'BTC-USD',
}
r = requests.post(api_url + 'orders', json=order, auth=auth)
print r.json()

---

Modified code:

import json, hmac, hashlib, time, requests, base64
from requests.auth import AuthBase

# Create custom authentication for Exchange
class CoinbaseExchangeAuth(AuthBase):
    def __init__(self, api_key, secret_key, passphrase):
        self.api_key = api_key
        self.secret_key = secret_key
        self.passphrase = passphrase

    def __call__(self, request):
        timestamp = str(time.time())
        message = timestamp + request.method + request.path_url + (request.body or b'').decode()
        hmac_key = base64.b64decode(self.secret_key)
        signature = hmac.new(hmac_key, message.encode(), hashlib.sha256)
        signature_b64 = base64.b64encode(signature.digest()).decode()

        request.headers.update({
            'CB-ACCESS-SIGN': signature_b64,
            'CB-ACCESS-TIMESTAMP': timestamp,
            'CB-ACCESS-KEY': self.api_key,
            'CB-ACCESS-PASSPHRASE': self.passphrase,
            'Content-Type': 'application/json'
        })
        return request

api_url = 'https://api.gdax.com/'
auth = CoinbaseExchangeAuth(APIKEY, API_SECRET,  API_PASS)

# Get accounts
r = requests.get(api_url + 'accounts', auth=auth)
print(r.json())
# [{"id": "a1b2c3d4", "balance":...

# Place an order
order = {
    'size': 1.0,
    'price': 1.0,
    'side': 'buy',
    'product_id': 'BTC-USD',
}
r = requests.post(api_url + 'orders', json=order, auth=auth)
print(r.json())

---

Note that i've only "translated" the original code, i can't guarantee for it's functionality or security.

Applicant

So, it is definitely working now, thank you a ton. But now I get this error. Traceback (most recent call last): File "a:\PythonCryptoBot\Bot1.0\CoinbaseExhangeAuth.py", line 88, in <module> print(r.json()) – Sectorial

Ok, that means that .json() failed to parse the response. Can you print r.text and r.status_code? – Applicant

And r.text? Is it json? – Applicant

when i try making a order r = requests.post(api_url + 'orders', json=order, auth=auth) i get the status code 405? which is not on the gdax api possible errors. huh... – Sectorial

That's strange, I tested with python2 and python3 and the headers are identical. The only difference is that signature_b64 is bytes, but that shouldn't be a problem. I fixed it anyway. I'll run a couple more tests, if i find anything useful i'll let you know – Applicant

switched to 2.7 to prevent further confusion - it does that same thing when i print(r.text). Spits out an entire html doc. And when I try to print(r.json()) it gives me a "ValueError: No JSON object could be decoded" – Sectorial

Then it must be about the url or post data, make sure they are correct. If you save r.text as .html file and open it in a browser it might give you a clue. – Applicant

Answer 2

The modified code you posted didn't quite work for me, but this did!

import hmac, hashlib, time, requests, os
from requests.auth import AuthBase


API_KEY = os.environ.get('API_KEY')
API_SECRET = os.environ.get('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 b'').decode()
        signature = hmac.new(bytes(self.secret_key,'utf-8'), message.encode('utf-8'), hashlib.sha256).hexdigest()

        request.headers.update({
            'CB-ACCESS-SIGN': signature,
            'CB-ACCESS-TIMESTAMP': timestamp,
            'CB-ACCESS-KEY': self.api_key,
            'CB-VERSION': '2019-11-15'
        })
        return request


api_url = 'https://api.coinbase.com/v2/'
auth = CoinbaseWalletAuth(API_KEY, API_SECRET)

# Get current user
r = requests.get(api_url + 'accounts', auth=auth)
print(r.json())

Undernourished