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TP04 finished and testes

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This commit is contained in:
Tiago Sousa 2024-03-16 17:11:11 +00:00
parent a6c894ed56
commit b726a165a4
Signed by: tiago
SSH key fingerprint: SHA256:odOD9vln9U7qNe1R8o3UCbE3jkQCkr5/q5mgd5hwua0
2 changed files with 77 additions and 47 deletions
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96
TPs/TP04/cfich_nike.py
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@ -1,11 +1,11 @@
import argparse
import os
import cryptography.hazmat.primitives.serialization as serialization
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import dh
from cryptography.hazmat.primitives.ciphers.aead import ChaCha20Poly1305
from cryptography.hazmat.primitives.kdf.hkdf import HKDF
import cryptography.hazmat.primitives.serialization as serialization
from cryptography.hazmat.primitives.serialization import (
Encoding,
NoEncryption,
@ -13,106 +13,125 @@ from cryptography.hazmat.primitives.serialization import (
PublicFormat,
)
p = 0x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
g = 2
params = dh.DHParameterNumbers(p, g).parameters()
def setup(user):
parameters = dh.generate_parameters(generator=2, key_size=512)
private_key = parameters.generate_private_key()
private_key = params.generate_private_key()
public_key = private_key.public_key()
skey = open(f"{user}.sk", 'wb')
pkey = open(f"{user}.pk", 'wb')
skey.write(private_key.private_bytes(encoding=Encoding.PEM, format=PrivateFormat.PKCS8, encryption_algorithm=NoEncryption()))
pkey.write(public_key.public_bytes(encoding=Encoding.PEM, format=PublicFormat.SubjectPublicKeyInfo))
skey = open(f"{user}.sk", "wb")
pkey = open(f"{user}.pk", "wb")
skey.write(
private_key.private_bytes(
encoding=Encoding.PEM,
format=PrivateFormat.PKCS8,
encryption_algorithm=NoEncryption(),
)
)
pkey.write(
public_key.public_bytes(
encoding=Encoding.PEM, format=PublicFormat.SubjectPublicKeyInfo
)
)
skey.close()
pkey.close()
def encrypt(user, filename):
peer_pkey_file = open(f"{user}.pk", 'rb')
peer_pkey_file = open(f"{user}.pk", "rb")
if peer_pkey_file is None:
print(f"No public key found for {user}")
return
file_r = open(filename, 'rb')
file_r = open(filename, "rb")
if file_r is None:
print(f"File {filename} not found")
return
# FIX: Add try
parameters = dh.generate_parameters(generator=2, key_size=512)
skey = parameters.generate_private_key()
skey = params.generate_private_key()
peer_pkey = serialization.load_pem_public_key(peer_pkey_file.read())
derived_key = None
if isinstance(peer_pkey, dh.DHPublicKey):
shared_key = skey.exchange(peer_pkey)
derived_key = HKDF(algorithm=hashes.SHA256(), length=32, salt=None, info=b'handshake data').derive(shared_key)
else:
if not isinstance(peer_pkey, dh.DHPublicKey):
print("Error: Invalid key type")
return
shared_key = skey.exchange(peer_pkey)
derived_key = HKDF(
algorithm=hashes.SHA256(), length=32, salt=None, info=None
).derive(shared_key)
message = file_r.read()
chacha = ChaCha20Poly1305(derived_key)
nonce = os.urandom(12)
ciphertext = chacha.encrypt(nonce, message, None)
file_w = open(f"{filename}.enc", 'wb')
nonce_ciphertext = mkpair(nonce, ciphertext)
to_send = mkpair(peer_pkey.public_bytes(Encoding.PEM, PublicFormat.SubjectPublicKeyInfo), nonce_ciphertext)
file_w = open(f"{filename}.enc", "wb")
nonce_ciphertext = nonce + ciphertext
pkey_bytes = skey.public_key().public_bytes(
Encoding.DER, PublicFormat.SubjectPublicKeyInfo
)
to_send = mkpair(pkey_bytes, nonce_ciphertext)
file_w.write(to_send)
file_r.close()
file_w.close()
skey_file.close()
peer_pkey_file.close()
def decrypt(user, filename):
skey_file = open(f"{user}.sk", 'rb')
skey_file = open(f"{user}.sk", "rb")
if skey_file is None:
print(f"No private key found for {user}")
return
file_r = open(filename, 'rb')
file_r = open(filename, "rb")
if file_r is None:
print(f"File {filename} not found")
return
message_bytes = file_r.read()
peer_pkey_bytes, ciphertext = unpair(message_bytes)
# FIX: Add try
skey = serialization.load_pem_private_key(skey_file.read(), None)
peer_pkey = serialization.load_pem_public_key(peer_pkey_bytes)
derived_key = None
if isinstance(skey, dh.DHPrivateKey) and isinstance(peer_pkey, dh.DHPublicKey):
shared_key = skey.exchange(peer_pkey)
derived_key = HKDF(algorithm=hashes.SHA256(), length=32, salt=None, info=b'handshake data').derive(shared_key)
else:
peer_pkey = serialization.load_der_public_key(peer_pkey_bytes)
if not isinstance(skey, dh.DHPrivateKey) or not isinstance(
peer_pkey, dh.DHPublicKey
):
print("Error: Invalid key type")
return
nonce, encrypted_message = unpair(ciphertext)
shared_key = skey.exchange(peer_pkey)
derived_key = HKDF(
algorithm=hashes.SHA256(), length=32, salt=None, info=None
).derive(shared_key)
nonce = ciphertext[:12]
encrypted_message = ciphertext[12:]
chacha = ChaCha20Poly1305(derived_key)
message = chacha.decrypt(nonce, encrypted_message, None)
file_w = open(f"{filename}.decrypt", 'wb')
file_w = open(f"{filename}.dec", "wb")
file_w.write(message)
file_r.close()
file_w.close()
skey_file.close()
def mkpair(x, y):
"""produz uma byte-string contendo o tuplo '(x,y)' ('x' e 'y' são byte-strings)"""
len_x = len(x)
len_x_bytes = len_x.to_bytes(2, 'little')
len_x_bytes = len_x.to_bytes(2, "little")
return len_x_bytes + x + y
def unpair(xy):
"""extrai componentes de um par codificado com 'mkpair'"""
len_x = int.from_bytes(xy[:2], 'little')
len_x = int.from_bytes(xy[:2], "little")
x = xy[2 : len_x + 2]
y = xy[len_x + 2 :]
return x, y
def main():
parser = argparse.ArgumentParser(
description="Program to perform operations using ChaCha20 cipher on files",
@ -121,7 +140,9 @@ def main():
subparsers = parser.add_subparsers(dest="operation", help="Operation to perform")
# Setup subcommand
setup_parser = subparsers.add_parser("setup", help="Setup diffie helman key pair for user")
setup_parser = subparsers.add_parser(
"setup", help="Setup diffie helman key pair for user"
)
setup_parser.add_argument("user", help="User for which to setup the key pair")
# Encrypt subcommand
@ -148,5 +169,6 @@ def main():
file = args.file
decrypt(user, file)
if __name__ == "__main__":
main()

8
TPs/TP04/input Normal file
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@ -0,0 +1,8 @@
As armas e os barões assinalados,
Que da ocidental praia Lusitana,
Por mares nunca de antes navegados,
Passaram ainda além da Taprobana,
Em perigos e guerras esforçados,
Mais do que prometia a força humana,
E entre gente remota edificaram
Novo Reino, que tanto sublimaram;