93 lines
2.6 KiB
Python
93 lines
2.6 KiB
Python
from cryptography.hazmat.primitives.ciphers.aead import ChaCha20Poly1305
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import argparse
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import os
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def setup(key_file):
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key = ChaCha20Poly1305.generate_key()
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with open(key_file, "wb") as f:
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f.write(key)
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def encrypt(input_file, key_file):
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with open(key_file, "rb") as f:
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key = f.read(32)
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with open(input_file, "rb") as f:
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plaintext = f.read()
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aad = b"authenticated but unencrypted data"
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nonce = os.urandom(12)
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cipher = ChaCha20Poly1305(key)
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ciphertext = cipher.encrypt(nonce, plaintext, aad)
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with open(f"{input_file}.enc", "wb") as f:
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f.write(nonce + ciphertext)
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def decrypt(input_file, key_file):
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with open(key_file, "rb") as f:
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key = f.read(32)
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with open(input_file, "rb") as f:
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input_bytes = f.read()
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aad = b"authenticated but unencrypted data"
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nonce = input_bytes[:12]
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ciphertext = input_bytes[12:]
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cipher = ChaCha20Poly1305(key)
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try:
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plaintext = cipher.decrypt(nonce, ciphertext, aad)
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except Exception as e:
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print(f"Could not validate the authentication: {e}")
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return
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with open(f"{input_file}.dec", "wb") as f:
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f.write(plaintext)
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def main():
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parser = argparse.ArgumentParser(
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description="Program to perform operations using Authenticated ChaCha20 cipher on files",
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)
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subparsers = parser.add_subparsers(dest="operation", help="Operation to perform")
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# Setup subcommand
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setup_parser = subparsers.add_parser("setup", help="Setup a key file")
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setup_parser.add_argument("fkey", help="File to contain the appropriate key for the ChaCha20 cipher")
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# Encrypt subcommand
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enc_parser = subparsers.add_parser("enc", help="Encrypt a file")
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enc_parser.add_argument("fich", help="File to be encrypted")
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enc_parser.add_argument("fkey", help="File containing the key for the ChaCha20 cipher")
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# Decrypt subcommand
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dec_parser = subparsers.add_parser("dec", help="Decrypt a file")
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dec_parser.add_argument("fich", help="File to be decrypted")
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dec_parser.add_argument("fkey", help="File containing the key for the ChaCha20 cipher")
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args = parser.parse_args()
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match args.operation:
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case "setup":
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key_file = args.fkey
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setup(key_file)
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case "enc":
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input_file = args.fich
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key_file = args.fkey
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encrypt(input_file,key_file)
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case "dec":
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input_file = args.fich
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key_file = args.fkey
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decrypt(input_file,key_file)
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case "help":
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parser.print_help()
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if __name__ == "__main__":
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main()
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