python 3 code for creating OTP code using TOTP algorithm

totp.py

import hashlib, hmac, time, base64, math

def totp_at(secret, digits, period, algorithm, t):
    counter = t // period
    counter_bytes = counter.to_bytes(8, byteorder='big')
    
    digest = hmac.new(secret, msg=counter_bytes, digestmod=algorithm).digest()
    
    offset = digest[-1] & 0x0F
    v_bytes = [ digest[offset] & 0x7F, digest[offset+1], digest[offset+2], digest[offset+3] ]
    v = int.from_bytes(v_bytes, byteorder='big')
    
    code = str(v % (10**digits))
    code = (digits - len(code))*'0' + code
    return code

def totp_now(secret, digits, period, algorithm):
    t = math.floor(time.time())
    return totp_at(secret, digits, period, algorithm, t)


secret = base64.b32decode('W2ASCT52EGQLJ42I5THBMEK2BYJ3Q5JRKIZLSEPNN4YW3KSLWQTH2LRSPAVUFFAY')
digits = 6
period = 30
algorithm = hashlib.sha1
code = totp_now(secret, digits, period, algorithm)
print(code)