50 lines
1.3 KiB
Python
50 lines
1.3 KiB
Python
import os
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import socket
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from Crypto.PublicKey import RSA
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from Crypto.Cipher import PKCS1_OAEP
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def recv_exact(conn: socket.socket, n: int) -> bytes:
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buf = b""
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while len(buf) < n:
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chunk = conn.recv(n - len(buf))
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if not chunk:
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raise ConnectionError("connection closed")
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buf += chunk
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return buf
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def main() -> None:
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host = "127.0.0.1"
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port = 5003
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default_msg = os.environ.get("LAB6_MESSAGE", "rsa hello")
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try:
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user_msg = input(f"Enter plaintext [{default_msg}]: ").strip()
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except EOFError:
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user_msg = ""
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message = (user_msg or default_msg).encode()
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with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as c:
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c.connect((host, port))
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# Receive server public key
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klen = int.from_bytes(recv_exact(c, 4), "big")
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kbytes = recv_exact(c, klen)
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server_pub = RSA.import_key(kbytes)
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# Encrypt message to server
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cipher = PKCS1_OAEP.new(server_pub)
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ctext = cipher.encrypt(message)
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c.sendall(len(ctext).to_bytes(4, "big") + ctext)
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# Receive acknowledgement
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rlen = int.from_bytes(recv_exact(c, 4), "big")
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reply = recv_exact(c, rlen)
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print("server reply:", reply.decode(errors="ignore"))
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if __name__ == "__main__":
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main()
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curl
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