def main():
# Argument validations
# Arguments must include flags:
server_address = input("Enter server address: ")
image_path = 'img\\' + input("Enter image name: ")
local_key_path = 'key\\' + input("Enter your private key name: ")
# Image instance
image = BMP(image_path)
# Diffie-Hellman process for generating a DES key
des_key = diffie_hellman((server_address, 12345))
# Key, cipher, hash and signer creation
key_file = open(local_key_path, 'r')
local_key = RSA.importKey(key_file.read())
key_file.close()
des_iv = b'12345678'
des_cipher = DES.new(des_key, DES.MODE_CBC, des_iv)
signer = Signature.new(local_key)
plaintext = image.pixels
hash = SHA.new(bytes(plaintext))
if len(plaintext) % 8 != 0:
padding = 8 - (len(plaintext) % 8)
plaintext += b'x' * padding
else:
padding = 0
ciphertext = des_cipher.encrypt(bytes(plaintext))
image.pixels = ciphertext
BMP.create_image(image, "cipher.bmp")
image_bytes = image.get_bytes()
signature = signer.sign(hash)
# Creating the connection with the server and sending
connection = socket.socket()
connection.connect((server_address, 12345))
connection.send('ci'.encode())
send_msg(connection, image_bytes)
send_msg(connection, signature)
connection.send(padding.to_bytes(1, 'little'))
def handle(self):
print('Processing request from {}'.format(self.client_address[0]))
type = self.connection.recv(2)
req = type.decode()
if req == 'dh':
print('Processing Diffie-Hellman')
g = random.randint(100, 9999999)
n = random.randint(10000000, 99999999)
gn_pair = str(g) + ' ' + str(n)
self.connection.send(gn_pair.encode()) # Send byte codification of g and n
remote_k = int.from_bytes(self.connection.recv(128), byteorder='little', signed=False)
# Prompt for local 'e' value and generate local key from g^e mod n
local_exponent = random.randint(100, 10000)
local_k = pow(g, local_exponent) % n # Generating the key
# Sending the local generated key in 128 unsigned byte length
self.connection.send(local_k.to_bytes(128, byteorder='little', signed=False))
# Finally generate the shared private key
k = str(pow(remote_k, local_exponent) % n).rjust(8, '0')
print('Done, private shared key: {}\n=======================\n'.format(k))
file = os.open("src\\server\\tmp\\" + self.client_address[0], os.O_CREAT | os.O_TRUNC | os.O_RDWR)
os.write(file, b'\x00'*8)
memory_file = mmap.mmap(file, 8)
memory_file.flush()
memory_file.write(k.encode())
elif req == 'ci':
print('Receiving image')
key_path = 'key\\' + input("Enter the sender's public key name: ")
key_file = open(key_path, 'rb')
key = RSA.importKey(key_file.read())
signer = Signature.new(key)
hash = SHA.new()
# Receiving the rest of the messages
# First the image
raw_image = recv_msg(self.connection)
# Then the signature
signature = recv_msg(self.connection)
# Finally the padding
raw_padding = self.connection.recv(1)
padding = int.from_bytes(raw_padding, 'little')
# Writing the ciphered image to a file
file = open('src\\server\\cipher.bmp', 'wb')
file.write(raw_image)
file.close()
image = BMP('src\\server\\cipher.bmp')
ciphertext = image.pixels
fd = os.open("src\\server\\tmp\\" + self.client_address[0], os.O_RDONLY, mode=0o555)
des_key = os.read(fd, 8)
decipher = DES.new(des_key, DES.MODE_CBC, b'12345678')
if padding == 0:
plaintext = decipher.decrypt(bytes(ciphertext))
else:
plaintext = decipher.decrypt(bytes(ciphertext))[:-padding]
image.pixels = plaintext
hash = SHA.new(plaintext)
signer = Signature.new(key)
if signer.verify(hash, signature):
print('Image signature validated, writing\n====================\n')
BMP.create_image(image, 'src\\server\\plain.bmp')
else:
print('Image signature invalid\n==============================\n')
self.finish()
def handle(self):
print('Processing request from {}'.format(self.client_address[0]))
type = self.connection.recv(2)
req = type.decode()
if req == 'dh':
print('Processing Diffie-Hellman')
g = random.randint(100, 9999999)
n = random.randint(10000000, 99999999)
gn_pair = str(g) + ' ' + str(n)
self.connection.send(
gn_pair.encode()) # Send byte codification of g and n
remote_k = int.from_bytes(self.connection.recv(128),
byteorder='little',
signed=False)
# Prompt for local 'e' value and generate local key from g^e mod n
local_exponent = random.randint(100, 10000)
local_k = pow(g, local_exponent) % n # Generating the key
# Sending the local generated key in 128 unsigned byte length
self.connection.send(
local_k.to_bytes(128, byteorder='little', signed=False))
# Finally generate the shared private key
k = str(pow(remote_k, local_exponent) % n).rjust(8, '0')
print('Done, private shared key: {}\n=======================\n'.
format(k))
file = os.open("src\\server\\tmp\\" + self.client_address[0],
os.O_CREAT | os.O_TRUNC | os.O_RDWR)
os.write(file, b'\x00' * 8)
memory_file = mmap.mmap(file, 8)
memory_file.flush()
memory_file.write(k.encode())
elif req == 'ci':
print('Receiving image')
key_path = 'key\\' + input("Enter the sender's public key name: ")
key_file = open(key_path, 'rb')
key = RSA.importKey(key_file.read())
signer = Signature.new(key)
hash = SHA.new()
# Receiving the rest of the messages
# First the image
raw_image = recv_msg(self.connection)
# Then the signature
signature = recv_msg(self.connection)
# Finally the padding
raw_padding = self.connection.recv(1)
padding = int.from_bytes(raw_padding, 'little')
# Writing the ciphered image to a file
file = open('src\\server\\cipher.bmp', 'wb')
file.write(raw_image)
file.close()
image = BMP('src\\server\\cipher.bmp')
ciphertext = image.pixels
fd = os.open("src\\server\\tmp\\" + self.client_address[0],
os.O_RDONLY,
mode=0o555)
des_key = os.read(fd, 8)
decipher = DES.new(des_key, DES.MODE_CBC, b'12345678')
if padding == 0:
plaintext = decipher.decrypt(bytes(ciphertext))
else:
plaintext = decipher.decrypt(bytes(ciphertext))[:-padding]
image.pixels = plaintext
hash = SHA.new(plaintext)
signer = Signature.new(key)
if signer.verify(hash, signature):
print(
'Image signature validated, writing\n====================\n'
)
BMP.create_image(image, 'src\\server\\plain.bmp')
else:
print(
'Image signature invalid\n==============================\n'
)
self.finish()