105 lines
3.6 KiB
Python
105 lines
3.6 KiB
Python
"""
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Generate and save RSA key pair
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"""
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import os
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from cryptography.hazmat.backends import default_backend
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from cryptography.hazmat.primitives import serialization
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from cryptography.hazmat.primitives.asymmetric import rsa
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class RSAKeyPair:
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"""
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Class for generating and saving RSA key pair
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"""
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def __init__(self, private_key_file, public_key_file):
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self.private_key_file = private_key_file
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self.public_key_file = public_key_file
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self.private_key = None
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self.public_key = None
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def generate_private_key(self):
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"""
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Generate RSA private key.
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The generated key has a 2048 bit length and a public exponent of 65537.
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"""
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self.private_key = rsa.generate_private_key(
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public_exponent=65537,
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key_size=2048,
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backend=default_backend()
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)
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def generate_public_key(self):
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"""
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Generate the public key from the private key.
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Raises:
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ValueError: Private key must be generated first.
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"""
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if self.private_key is None:
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raise ValueError("Private key must be generated first.")
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self.public_key = self.private_key.public_key()
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def save_private_key(self):
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"""
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Save the generated private key to a file.
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The private key is saved in PEM format with the Traditional OpenSSL
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format and no encryption. If the private key has not been generated yet,
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a ValueError is raised.
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Raises:
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ValueError: Private key must be generated before saving.
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"""
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if self.private_key is None:
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raise ValueError("Private key must be generated before saving.")
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with open(self.private_key_file, 'wb') as f:
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f.write(self.private_key.private_bytes(
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encoding=serialization.Encoding.PEM,
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format=serialization.PrivateFormat.TraditionalOpenSSL,
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encryption_algorithm=serialization.NoEncryption()
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))
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def save_public_key(self):
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"""
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Save the generated public key to a file.
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The public key is saved in PEM format with the SubjectPublicKeyInfo
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format. If the public key has not been generated yet, a ValueError is
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raised.
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Raises:
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ValueError: Public key must be generated before saving.
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"""
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if self.public_key is None:
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raise ValueError("Public key must be generated before saving.")
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with open(self.public_key_file, 'wb') as f:
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f.write(self.public_key.public_bytes(
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encoding=serialization.Encoding.PEM,
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format=serialization.PublicFormat.SubjectPublicKeyInfo
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))
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def generate_and_save_keys(self):
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"""
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Generate and save the private and public keys to the specified files.
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This method first checks if the key files already exist. If not, it
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generates the private key and saves it to the private key file, and
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generates the public key based on the private key and saves it to the
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public key file. If the files already exist, it simply prints a message
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to the console.
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This method does not raise any exceptions if the files already exist.
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"""
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if not os.path.exists(self.private_key_file) and not os.path.exists(self.public_key_file):
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try:
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self.generate_private_key()
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self.save_private_key()
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self.generate_public_key()
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self.save_public_key()
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except ValueError as e:
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print(e)
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