3-sign-verify.py

# import hmac library
import hmac

# configure a key
HMAC_KEY = 'O\x8cNd\x16E\xb1U\x1b\x0b\xe8\t\xd8\xab\xbcI'

# change signing function to use hmac
ctx = hmac.new(KEY, digestmod=hashlib.sha256)
ctx.update(request.args["data"])
digest = ctx.hexdigest()

# change verification function to use hmac
ctx = hmac.new(KEY, digestmod=hashlib.sha256)
ctx.update(request.args["data"])
computed_digest = ctx.hexdigest().decode('utf8')
if hmac.compare_digest(request.args["digest"], computed_digest):