Python/ciphers/cryptomath_module.py
Christian Clauss 4b79d771cd
Add more ruff rules (#8767)
* Add more ruff rules

* Add more ruff rules

* pre-commit: Update ruff v0.0.269 -> v0.0.270

* Apply suggestions from code review

* Fix doctest

* Fix doctest (ignore whitespace)

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

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Co-authored-by: Dhruv Manilawala <dhruvmanila@gmail.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
2023-05-26 09:34:17 +02:00

17 lines
447 B
Python

def gcd(a: int, b: int) -> int:
while a != 0:
a, b = b % a, a
return b
def find_mod_inverse(a: int, m: int) -> int:
if gcd(a, m) != 1:
msg = f"mod inverse of {a!r} and {m!r} does not exist"
raise ValueError(msg)
u1, u2, u3 = 1, 0, a
v1, v2, v3 = 0, 1, m
while v3 != 0:
q = u3 // v3
v1, v2, v3, u1, u2, u3 = (u1 - q * v1), (u2 - q * v2), (u3 - q * v3), v1, v2, v3
return u1 % m