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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/randnum.py | |
| parent | cc961e04ba734dd72309fb548a2f97d67d578813 (diff) | |
| download | gn-ai-master.tar.gz | |
Diffstat (limited to '.venv/lib/python3.12/site-packages/rsa/randnum.py')
| -rw-r--r-- | .venv/lib/python3.12/site-packages/rsa/randnum.py | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/rsa/randnum.py b/.venv/lib/python3.12/site-packages/rsa/randnum.py new file mode 100644 index 00000000..bb255c57 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/rsa/randnum.py @@ -0,0 +1,95 @@ +# 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 generating random numbers.""" + +# Source inspired by code by Yesudeep Mangalapilly <yesudeep@gmail.com> + +import os +import struct + +from rsa import common, transform + + +def read_random_bits(nbits: int) -> bytes: + """Reads 'nbits' random bits. + + If nbits isn't a whole number of bytes, an extra byte will be appended with + only the lower bits set. + """ + + nbytes, rbits = divmod(nbits, 8) + + # Get the random bytes + randomdata = os.urandom(nbytes) + + # Add the remaining random bits + if rbits > 0: + randomvalue = ord(os.urandom(1)) + randomvalue >>= 8 - rbits + randomdata = struct.pack("B", randomvalue) + randomdata + + return randomdata + + +def read_random_int(nbits: int) -> int: + """Reads a random integer of approximately nbits bits.""" + + randomdata = read_random_bits(nbits) + value = transform.bytes2int(randomdata) + + # Ensure that the number is large enough to just fill out the required + # number of bits. + value |= 1 << (nbits - 1) + + return value + + +def read_random_odd_int(nbits: int) -> int: + """Reads a random odd integer of approximately nbits bits. + + >>> read_random_odd_int(512) & 1 + 1 + """ + + value = read_random_int(nbits) + + # Make sure it's odd + return value | 1 + + +def randint(maxvalue: int) -> int: + """Returns a random integer x with 1 <= x <= maxvalue + + May take a very long time in specific situations. If maxvalue needs N bits + to store, the closer maxvalue is to (2 ** N) - 1, the faster this function + is. + """ + + bit_size = common.bit_size(maxvalue) + + tries = 0 + while True: + value = read_random_int(bit_size) + if value <= maxvalue: + break + + if tries % 10 == 0 and tries: + # After a lot of tries to get the right number of bits but still + # smaller than maxvalue, decrease the number of bits by 1. That'll + # dramatically increase the chances to get a large enough number. + bit_size -= 1 + tries += 1 + + return value |