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| author | S. Solomon Darnell | 2025-03-28 21:52:21 -0500 |
|---|---|---|
| committer | S. Solomon Darnell | 2025-03-28 21:52:21 -0500 |
| commit | 4a52a71956a8d46fcb7294ac71734504bb09bcc2 (patch) | |
| tree | ee3dc5af3b6313e921cd920906356f5d4febc4ed /.venv/lib/python3.12/site-packages/rsa/pkcs1_v2.py | |
| parent | cc961e04ba734dd72309fb548a2f97d67d578813 (diff) | |
| download | gn-ai-master.tar.gz | |
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") |