84 lines
2.6 KiB
Python
84 lines
2.6 KiB
Python
import hashlib
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from typing import Any, Optional
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from . import utils
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from .otp import OTP
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class HOTP(OTP):
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"""
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Handler for HMAC-based OTP counters.
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"""
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def __init__(
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self,
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s: str,
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digits: int = 6,
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digest: Any = None,
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name: Optional[str] = None,
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issuer: Optional[str] = None,
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initial_count: int = 0,
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) -> None:
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"""
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:param s: secret in base32 format
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:param initial_count: starting HMAC counter value, defaults to 0
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:param digits: number of integers in the OTP. Some apps expect this to be 6 digits, others support more.
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:param digest: digest function to use in the HMAC (expected to be SHA1)
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:param name: account name
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:param issuer: issuer
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"""
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if digest is None:
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digest = hashlib.sha1
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self.initial_count = initial_count
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super().__init__(s=s, digits=digits, digest=digest, name=name, issuer=issuer)
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def at(self, count: int) -> str:
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"""
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Generates the OTP for the given count.
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:param count: the OTP HMAC counter
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:returns: OTP
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"""
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return self.generate_otp(self.initial_count + count)
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def verify(self, otp: str, counter: int) -> bool:
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"""
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Verifies the OTP passed in against the current counter OTP.
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:param otp: the OTP to check against
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:param counter: the OTP HMAC counter
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"""
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return utils.strings_equal(str(otp), str(self.at(counter)))
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def provisioning_uri(
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self,
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name: Optional[str] = None,
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initial_count: Optional[int] = None,
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issuer_name: Optional[str] = None,
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image: Optional[str] = None,
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) -> str:
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"""
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Returns the provisioning URI for the OTP. This can then be
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encoded in a QR Code and used to provision an OTP app like
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Google Authenticator.
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See also:
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https://github.com/google/google-authenticator/wiki/Key-Uri-Format
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:param name: name of the user account
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:param initial_count: starting HMAC counter value, defaults to 0
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:param issuer_name: the name of the OTP issuer; this will be the
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organization title of the OTP entry in Authenticator
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:returns: provisioning URI
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"""
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return utils.build_uri(
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self.secret,
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name=name if name else self.name,
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initial_count=initial_count if initial_count else self.initial_count,
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issuer=issuer_name if issuer_name else self.issuer,
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algorithm=self.digest().name,
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digits=self.digits,
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image=image,
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)
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