OXIESEC PANEL

Name	Size	Modified	Perms
📁 ..	-	12/11/2024 09:39:44 AM	rwxr-xr-x
📄 __init__.py	1.51 KB	04/05/2021 03:08:16 PM	rw-r--r--
📁 __pycache__	-	02/11/2025 08:19:48 AM	rwxr-xr-x
📄 _compat.py	4.24 KB	04/05/2021 03:08:16 PM	rw-r--r--
📄 asn1.py	1.74 KB	04/05/2021 03:08:16 PM	rw-r--r--
📄 cli.py	8.99 KB	04/05/2021 03:08:16 PM	rw-r--r--
📄 common.py	4.46 KB	04/05/2021 03:08:16 PM	rw-r--r--
📄 core.py	1.62 KB	04/05/2021 03:08:16 PM	rw-r--r--
📄 key.py	23.96 KB	04/05/2021 03:08:16 PM	rw-r--r--
📄 machine_size.py	2.3 KB	04/05/2021 03:08:16 PM	rw-r--r--
📄 parallel.py	2.27 KB	04/05/2021 03:08:16 PM	rw-r--r--
📄 pem.py	3.48 KB	04/05/2021 03:08:16 PM	rw-r--r--
📄 pkcs1.py	14.35 KB	04/05/2021 03:08:16 PM	rw-r--r--
📄 pkcs1_v2.py	3.38 KB	04/05/2021 03:08:16 PM	rw-r--r--
📄 prime.py	4.95 KB	04/05/2021 03:08:16 PM	rw-r--r--
📄 randnum.py	2.58 KB	04/05/2021 03:08:16 PM	rw-r--r--
📄 transform.py	6.44 KB	04/05/2021 03:08:16 PM	rw-r--r--
📄 util.py	2.99 KB	04/05/2021 03:08:16 PM	rw-r--r--

Editing: pkcs1_v2.py

# -*- coding: utf-8 -*-
#
#  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._compat import range
from rsa import (
    common,
    pkcs1,
    transform,
)

def mgf1(seed, length, hasher='SHA-1'):
    """
    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:
        raise ValueError(
            'Invalid `hasher` specified. Please select one of: {hash_list}'.format(
                hash_list=', '.join(sorted(pkcs1.HASH_METHODS.keys()))
            )
        )

# 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')