def recv_next_command(conn: socket, client_parser=None):
"""
waits for a command by the client, and returns the parsed args,
responds to the client with 202 and data on success
:param conn: socket connection
:return: client command arguments, or None if invalid command
"""
command_json = _bytes_to_string(recv_msg(conn))
print("received req:", command_json)
try:
#
#
#
client_args = { # extend defaults
'file_index': None,
'local': False,
'key': DEFAULT_KEY,
'cipher': 'none',
'filename': '',
'function': lambda x: None,
'iv': None,
}
client_args.update(json.loads(command_json)) # update
client_args = AttrDict(client_args)
# converting args (parsing strings to bytes and function names to functions)
client_args.cipherfunc = getattr(CipherLib, client_args.cipher)
client_args.iv = _string_to_bytes(client_args.iv)
client_args.function = eval(client_args.function)
# printing object:
import pprint
pp = pprint.PrettyPrinter(indent=4)
print('client_args received')
pp.pprint(vars(client_args))
#
server_resp = _string_to_bytes(
json.dumps({
'readystate': 202, # code "202" meaning (accepted)
}))
send_msg(conn, server_resp)
return client_args
except Exception as e:
print("ERROR executing command:", e)
return None
def send_command(args, callback=lambda sock: print("Connected", sock)):
"""connects to the server and sends the command
:param args: this object is similar to the one parsed from the commandline,
contains "host" and "port" members
:param callback(sock, respjson): a function to call when connected to the server.
sock: Gets passed the socket object, the socket object at this point is already connected and is ready to send or recv.
:return the callback result
"""
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
print('connecting to server...', end='')
s.connect((args.host, args.port)) # connect
print('\rConnection established ')
# random initialization vector
setattr(args, 'iv', secrets.token_bytes(16))
if not hasattr(args, 'cipherfunc'):
setattr(args, 'cipherfunc', CipherLib.none)
################
# serialize args
################
import copy
s_args = copy.deepcopy(vars(args))
for k, v in s_args.items():
if isinstance(v,
types.FunctionType): # functions get the name passed
s_args[k] = v.__name__
elif isinstance(v, bytes): # bytes get turned into strings
s_args[k] = _bytes_to_string(v)
s_args['cipher'] = s_args.get('cipherfunc', 'none')
del s_args['key'] # delete key (otherwise is sent in plaintext)
request_json = json.dumps(s_args)
print('Sending command: "{}"'.format(request_json))
# send the command/request json
send_msg(s, _string_to_bytes(request_json))
# check if server acknowledged the command
# (if resp is included in one of the success response codes)
resp = recv_msg(s)
resp_json = AttrDict(json.loads(_bytes_to_string(resp)))
if resp_json.readystate in [202]:
res = callback(s)
send_msg(s, b'200') # send OK code
print('\nTransaction complete')
return res
def callback(conn: socket):
ciphertext = b''
with open(filename, 'rb') as f:
data = f.read()
ciphertext = args.cipherfunc(data=data, key=args.key, iv=args.iv)
return send_msg(
conn,
_string_to_bytes(
json.dumps({
'filename': filename,
'data': _bytes_to_string(ciphertext),
'iv': _bytes_to_string(args.iv),
})))
def get(conn: socket, args=None):
# send the file to client
if args.file_index:
args.filename = os.listdir('files')[int(args.filename)]
iv = secrets.token_bytes(16)
args_filename = args.filename
filename = os.path.join('files', args_filename)
with open(filename, 'rb') as f:
plaintext = f.read()
ciphertext = args.cipherfunc(data=plaintext, key=args.key, iv=iv)
print("finished reading file \"{}\", {}B".format(filename,
len(ciphertext)))
return send_msg(
conn,
_string_to_bytes(
json.dumps({
'filename': filename,
'data': _bytes_to_string(ciphertext),
'iv': _bytes_to_string(iv),
})))
def main():
"""
Step 1: Alice generates an RSA key pair PK=(n,e) and SK=(d) and generates two random values, r_0 and r_1, and sends them to Bob along with her PK
Step 2: Bob picks a bit b to be either 0 or 1, and selects r_b
Step 3: Bob generates a random value k and blinds r_b by computing 〖v=r〗_b+k^e mod n and send it to Alice
Step 4: Alice doesn't know which of r_0 and r_1 Bob chose.
She applies them both and come up with two possible values for k:k_0=(v−x_0 )^d mod n and k_1=(v−x_1 )^d mod n
Eventually,
one of these will be equal to k and can be correctly decrypted by Bob (but not Alice),
while the other will produce a meaningless random value that does not reveal any information about k
Step 5: Alice combines the two secret messages with each of the possible keys, m_0^′=m_0+k_0 and m_1^′=m_1+k_1, and sends them both to Bob
Step 6: Bob knows which of the two messages can be unblinded with k, so he is able to compute exactly one of the messages m_b=m_b^′−k
:return:
"""
parser = get_arg_parser()
print(DESCRIPTION + "\n")
args = parser.parse_args()
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
print('connecting to server...', end='')
s.connect((args.host, args.port)) # connect
print('\rConnection established ')
# recv public key
resp = recv_msg(s)
resp = json.loads(_bytes_to_string(resp))
alice_pubkey = rsa.PublicKey(resp['n'], resp['e'])
r_b_choices = list(map(_string_to_bytes, resp['r_b_choices']))
print('alice_pubkey', alice_pubkey)
print('r_b_choices', r_b_choices)
# Step 2: Bob picks a bit b to be either 0 or 1, and selects r_bs
r_b = int.from_bytes(r_b_choices[args.msg_index], 'big')
# Step 3: Bob generates a random value k and blinds r_b by computing 〖v=r〗_b+k^e mod n and send it to Alice
k = secrets.token_bytes(4)
k_int = int.from_bytes(k, 'big')
print('k=', k_int)
print('r_b=', r_b)
v = _string_to_bytes(str(alice_pubkey.blind(r_b, k_int)))
print('v=', v)
send_msg(s, v)
# Step 6: Bob knows which of the two messages can be unblinded with k, so he is able to compute exactly one of the messages m_b=m_b^′−k
resp6 = recv_msg(s)
resp6_str = _bytes_to_string(resp6)
print('resp6_str=', resp6_str)
combined_list = resp6_str.split(',')
combined_list = list(map(_string_to_bytes, combined_list))
f = Fernet(k)
# value = combined_list[args.msg_index] ^ k_int
value = f.decrypt(combined_list[args.msg_index])
print('the value is:', value)
if resp in [202]:
send_msg(s, b'200') # send OK code
print('\nTransaction complete')
def ls(conn: socket, args=None):
# send list of files
filelist = os.listdir('files/')
filelist_json = json.dumps(filelist)
send_msg(conn, _string_to_bytes(filelist_json))
# Step 1: Alice generates an RSA key pair PK=(n,e) and SK=(d)
pubkey, privkey = rsa.newkeys(32, poolsize=8)
print(pubkey)
print(privkey)
# generates n random values, r_0 and r_1, and sends them to Bob along with her PK
r_b_choices = [secrets.token_bytes(4) for i in range(args.n_msgs)]
json_string = json.dumps({
'e': pubkey.e,
'n': pubkey.n,
'r_b_choices': list(map(_bytes_to_string, r_b_choices)),
})
send_msg(conn, _string_to_bytes(json_string))
# Step 4: Alice doesn't know which of r_0 and r_1 Bob chose.
# She applies them both and come up with two possible values for k:k_0=(v−x_0 )^d mod n and k_1=(v−x_1 )^d mod n Eventually,
# one of these will be equal to k and can be correctly decrypted by Bob (but not Alice),
# while the other will produce a meaningless random value that does not reveal any information about k
resp4 = recv_msg(conn)
v = _bytes_to_string(resp4)
print('v=', v)
print('r_b_choices=', r_b_choices)
k_list = [privkey.unblind(v, int.from_bytes(r_b, 'big')) for r_b in r_b_choices]
print('k_list=', k_list)
# combining the message with the key: m' = m+k
# combined_msgs = [messages[i] ^ k_list[i] for i in range(args.n_msgs)]