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File Content: `padding.py`

# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.

from __future__ import annotations

import abc

from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives._asymmetric import (
    AsymmetricPadding as AsymmetricPadding,
)
from cryptography.hazmat.primitives.asymmetric import rsa


class PKCS1v15(AsymmetricPadding):
    name = "EMSA-PKCS1-v1_5"


class _MaxLength:
    "Sentinel value for `MAX_LENGTH`."


class _Auto:
    "Sentinel value for `AUTO`."


class _DigestLength:
    "Sentinel value for `DIGEST_LENGTH`."


class PSS(AsymmetricPadding):
    MAX_LENGTH = _MaxLength()
    AUTO = _Auto()
    DIGEST_LENGTH = _DigestLength()
    name = "EMSA-PSS"
    _salt_length: int | _MaxLength | _Auto | _DigestLength

    def __init__(
        self,
        mgf: MGF,
        salt_length: int | _MaxLength | _Auto | _DigestLength,
    ) -> None:
        self._mgf = mgf

        if not isinstance(
            salt_length, (int, _MaxLength, _Auto, _DigestLength)
        ):
            raise TypeError(
                "salt_length must be an integer, MAX_LENGTH, "
                "DIGEST_LENGTH, or AUTO"
            )

        if isinstance(salt_length, int) and salt_length < 0:
            raise ValueError("salt_length must be zero or greater.")

        self._salt_length = salt_length

    @property
    def mgf(self) -> MGF:
        return self._mgf


class OAEP(AsymmetricPadding):
    name = "EME-OAEP"

    def __init__(
        self,
        mgf: MGF,
        algorithm: hashes.HashAlgorithm,
        label: bytes | None,
    ):
        if not isinstance(algorithm, hashes.HashAlgorithm):
            raise TypeError("Expected instance of hashes.HashAlgorithm.")

        self._mgf = mgf
        self._algorithm = algorithm
        self._label = label

    @property
    def algorithm(self) -> hashes.HashAlgorithm:
        return self._algorithm

    @property
    def mgf(self) -> MGF:
        return self._mgf


class MGF(metaclass=abc.ABCMeta):
    _algorithm: hashes.HashAlgorithm


class MGF1(MGF):
    MAX_LENGTH = _MaxLength()

    def __init__(self, algorithm: hashes.HashAlgorithm):
        if not isinstance(algorithm, hashes.HashAlgorithm):
            raise TypeError("Expected instance of hashes.HashAlgorithm.")

        self._algorithm = algorithm


def calculate_max_pss_salt_length(
    key: rsa.RSAPrivateKey | rsa.RSAPublicKey,
    hash_algorithm: hashes.HashAlgorithm,
) -> int:
    if not isinstance(key, (rsa.RSAPrivateKey, rsa.RSAPublicKey)):
        raise TypeError("key must be an RSA public or private key")
    # bit length - 1 per RFC 3447
    emlen = (key.key_size + 6) // 8
    salt_length = emlen - hash_algorithm.digest_size - 2
    assert salt_length >= 0
    return salt_length

Name	Size	Permission
__pycache__	---	0755
__init__.py	180 bytes	0644
dh.py	3420 bytes	0644
dsa.py	3945 bytes	0644
ec.py	10428 bytes	0644
ed25519.py	3423 bytes	0644
ed448.py	3456 bytes	0644
padding.py	2885 bytes	0644
rsa.py	7637 bytes	0644
types.py	2996 bytes	0644
utils.py	790 bytes	0644
x25519.py	3341 bytes	0644
x448.py	3374 bytes	0644

File Content: padding.py

File Content: `padding.py`