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kirbylife 2024-01-27 06:05:19 +00:00
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# Implementation of the TOTP algorithm in Python
```Python
from hashlib import sha1
from datetime import datetime
from base64 import b32decode
INTERVAL = 30
TOTP_KEY = "BOMY6BV5BWVJEWJ4ZLDYKN3LSIS736B3"
def generate():
# Pre-process data
epoch = datetime.now().timestamp()
msg = int(epoch) // INTERVAL
bytes_msg = msg.to_bytes(8, byteorder="big")
key_decoded = b32decode(TOTP_KEY, casefold=True)
# HMAC-SHA1
key_pad = key_decoded.ljust(64, b"\0")
i_key_pad = bytes(x ^ 0x36 for x in key_pad)
o_key_pad = bytes(x ^ 0x5C for x in key_pad)
i_key_pad_msg = i_key_pad + bytes_msg
i_key_pad_msg_hashed = sha1(i_key_pad_msg).digest()
o_key_pad_msg = o_key_pad + i_key_pad_msg_hashed
hmac_result = sha1(o_key_pad_msg).digest()
# TOTP Algorithm
start = hmac_result[19] & 0xF
raw_bytes = hmac_result[start:start + 4]
raw_token = int.from_bytes(raw_bytes, byteorder="big")
raw_token = raw_token & 0x7F_FF_FF_FF
token = raw_token % 1_000_000
print(str(token).rjust(6, "0"))
```