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Hermann-SW/generate_rsa_keys_from_p_and_q.py

Created July 31, 2025 14:39
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generate_rsa_keys_from_p_and_q.py
""" pylinted, and code formatted with black """
from math import lcm
from cryptography.hazmat.primitives.asymmetric import rsa
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import serialization
# P and Q are prime factors of largest factored sofar RSA-250
#
P = 641352894770715802787901901705773890848250147429434472081168596 * 10**62
P += 32024532344630238623598752668347708737661925585694639798853367
Q = 333720275949781565562260106053551142279407603447675546667845209 * 10**62
Q += 87023841729210037080257448673296881877565718986258036932062711
E = 0x10001
L = lcm(P - 1, Q - 1)
private_key = rsa.RSAPrivateNumbers(
p=P,
q=Q,
d=pow(E, -1, L),
dmp1=pow(E, -1, P - 1),
dmq1=pow(E, -1, Q - 1),
iqmp=pow(Q, -1, P),
public_numbers=rsa.RSAPublicNumbers(e=E, n=P * Q),
).private_key(default_backend())
pem = private_key.private_bytes(
encoding=serialization.Encoding.PEM,
encryption_algorithm=serialization.NoEncryption(),
format=serialization.PrivateFormat.TraditionalOpenSSL,
)
with open("private_key.pem", "wb") as f:
f.write(pem)
public_key = private_key.public_key()
pem = public_key.public_bytes(
encoding=serialization.Encoding.PEM,
format=serialization.PublicFormat.SubjectPublicKeyInfo,
)
with open("public_key.pem", "wb") as f:
f.write(pem)
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Hermann-SW commented Jul 31, 2025

Using openssl with deprecated rsautl can be seen in this gist comment:
https://gist.github.com/Hermann-SW/4aefd5b12ff179700bb6594ba25f9646?permalink_comment_id=5701082#gistcomment-5701082

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