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Diffstat (limited to '.venv/lib/python3.12/site-packages/rsa/pkcs1_v2.py')
-rw-r--r-- | .venv/lib/python3.12/site-packages/rsa/pkcs1_v2.py | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/rsa/pkcs1_v2.py b/.venv/lib/python3.12/site-packages/rsa/pkcs1_v2.py new file mode 100644 index 00000000..cc2c3170 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/rsa/pkcs1_v2.py @@ -0,0 +1,100 @@ +# Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Functions for PKCS#1 version 2 encryption and signing
+
+This module implements certain functionality from PKCS#1 version 2. Main
+documentation is RFC 2437: https://tools.ietf.org/html/rfc2437
+"""
+
+from rsa import (
+ common,
+ pkcs1,
+ transform,
+)
+
+
+def mgf1(seed: bytes, length: int, hasher: str = "SHA-1") -> bytes:
+ """
+ MGF1 is a Mask Generation Function based on a hash function.
+
+ A mask generation function takes an octet string of variable length and a
+ desired output length as input, and outputs an octet string of the desired
+ length. The plaintext-awareness of RSAES-OAEP relies on the random nature of
+ the output of the mask generation function, which in turn relies on the
+ random nature of the underlying hash.
+
+ :param bytes seed: seed from which mask is generated, an octet string
+ :param int length: intended length in octets of the mask, at most 2^32(hLen)
+ :param str hasher: hash function (hLen denotes the length in octets of the hash
+ function output)
+
+ :return: mask, an octet string of length `length`
+ :rtype: bytes
+
+ :raise OverflowError: when `length` is too large for the specified `hasher`
+ :raise ValueError: when specified `hasher` is invalid
+ """
+
+ try:
+ hash_length = pkcs1.HASH_METHODS[hasher]().digest_size
+ except KeyError as ex:
+ raise ValueError(
+ "Invalid `hasher` specified. Please select one of: {hash_list}".format(
+ hash_list=", ".join(sorted(pkcs1.HASH_METHODS.keys()))
+ )
+ ) from ex
+
+ # If l > 2^32(hLen), output "mask too long" and stop.
+ if length > (2 ** 32 * hash_length):
+ raise OverflowError(
+ "Desired length should be at most 2**32 times the hasher's output "
+ "length ({hash_length} for {hasher} function)".format(
+ hash_length=hash_length,
+ hasher=hasher,
+ )
+ )
+
+ # Looping `counter` from 0 to ceil(l / hLen)-1, build `output` based on the
+ # hashes formed by (`seed` + C), being `C` an octet string of length 4
+ # generated by converting `counter` with the primitive I2OSP
+ output = b"".join(
+ pkcs1.compute_hash(
+ seed + transform.int2bytes(counter, fill_size=4),
+ method_name=hasher,
+ )
+ for counter in range(common.ceil_div(length, hash_length) + 1)
+ )
+
+ # Output the leading `length` octets of `output` as the octet string mask.
+ return output[:length]
+
+
+__all__ = [
+ "mgf1",
+]
+
+if __name__ == "__main__":
+ print("Running doctests 1000x or until failure")
+ import doctest
+
+ for count in range(1000):
+ (failures, tests) = doctest.testmod()
+ if failures:
+ break
+
+ if count % 100 == 0 and count:
+ print("%i times" % count)
+
+ print("Doctests done")
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