I am attempting to utilize Duo MFA's - Admin API. It requires Date and Authorization headers to have a signed canonical string which I am having trouble with.
My current code:
import base64, email, hmac, hashlib, urllib, requests
url = "admin api link"
ikey = "secret"
skey = "secret"
def sign(method, host, path, params, skey, ikey):
    """
    Return HTTP Basic Authentication ("Authorization" and "Date") headers.
    method, host, path: strings from request
    params: dict of request parameters
    skey: secret key
    ikey: integration key
    """
    # create canonical string
    now = email.Utils.formatdate()
    canon = [now, method.upper(), host.lower(), path]
    args = []
    for key in sorted(params.keys()):
        val = params[key]
        if isinstance(val, unicode):
            val = val.encode("utf-8")
        args.append(
            '%s=%s' % (urllib.quote(key, '~'), urllib.quote(val, '~')))
    canon.append('&'.join(args))
    canon = '\n'.join(canon)
    # sign canonical string
    sig = hmac.new(skey, canon, hashlib.sha1)
    auth = '%s:%s' % (ikey, sig.hexdigest())
    # return headers
    return {'Date': now, 'Authorization': 'Basic %s' % base64.b64encode(auth)}
headers = {
    'Date': ?,
    'Authorization': ?,
    }
response = requests.request("GET", url, headers=headers)
print(response.text)
How can I set the headers to use the sign functions return Date and Authorization? 
I have tried sign(Date) and sign(Authorization) with no luck. I believe I am missing some fundamental/rudimentary python logic on using the returns from functions.
 
    