Verify slack requests for slash commands in python3

verify_slack_request.py

#!/usr/bin/env python3
import hashlib
import hmac
import base64


def verify_slack_request(event: dict, slack_signing_secret: str) -> bool:
    """Verify slack requests.

    Borrowed from https://janikarhunen.fi/verify-slack-requests-in-aws-lambda-and-python.html

    - Removed optional args
    - Checks isBase64Encoded

    :param event: standard event handler
    :param slack_signing_secret: slack secret for the slash command
    :return: True if verification worked
    """
    slack_signature = event['headers']['x-slack-signature']
    slack_time = event['headers']['x-slack-request-timestamp']
    body = event['body']
    if event['isBase64Encoded']:
        body = base64.b64decode(body).decode("utf-8")

    # Form the basestring as stated in the Slack API docs. We need to make a bytestring.
    base_string = f'v0:{slack_time}:{body}'.encode('utf-8')

    # Make the Signing Secret a bytestring too.
    slack_signing_secret = bytes(slack_signing_secret, 'utf-8')

    # Create a new HMAC "signature", and return the string presentation.
    my_signature = 'v0=' + hmac.new(
        slack_signing_secret, base_string, hashlib.sha256
    ).hexdigest()

    ''' Compare the the Slack provided signature to ours.
    If they are equal, the request should be verified successfully.
    Log the unsuccessful requests for further analysis
    (along with another relevant info about the request).'''
    result = hmac.compare_digest(my_signature, slack_signature)
    if not result:
        logger.error('Verification failed. my_signature: ')
        logger.error(f'{my_signature} != {slack_signature}')

    return result


if __name__ == '__main__':
    # add correct params here
    print(verify_slack_request({}, None))