def centralServer(id, Key = "", nonce = ""):
channel = grpc.insecure_channel('localhost:50051')
stub = central_grpc.CentralStub(channel)
servers = []
""" choose service from stub and then proto message from pb
serialized message with respect to the proto """
if nonce == "":
response = stub.GiveFS(centralpb.Request(name = str(id))).name.encode()
fernet = Fernet(Key.encode())
plaintext = fernet.decrypt(response).decode()
servers = plaintext.split(" ")
print("The Number of File Servers active are {}.\nSelect the File Server to establish communication:\n".format(len(servers)))
for i, s in enumerate(servers):
print(i + 1, ") " + s)
else:
# print(id.decode(), type(id))
response = stub.Registration(centralpb.Request(name = id.decode()))
fernet = Fernet(Key.encode())
plaintext = fernet.decrypt(response.name.encode()).decode()
if int(plaintext) + 1 == int(nonce):
print("Registration complete successfully.")
return servers
def sendToCentral(id, nonce="", Key=""):
channel = grpc.insecure_channel('localhost:50051')
stub = central_grpc.CentralStub(channel)
response = stub.Registration(centralpb.Request(name=id))
fernet = Fernet(Key.encode())
plaintext = fernet.decrypt(response.name.encode()).decode()
if int(plaintext) + 1 == int(nonce):
print("Registration complete successfully.")
def checkCenter(key, pid):
fernet = Fernet(key.encode())
channel = grpc.insecure_channel('localhost:50051')
stub = central_grpc.CentralStub(channel)
response = stub.GetUpdate(centralpb.Request(name = pid))
plaintext = fernet.decrypt(response.name.encode()).decode()
if len(plaintext) == 0:
return
print("\nThe following files have been added : FileName[FileServer]\n")
plaintext = plaintext.split()
for i,p in enumerate(plaintext):
print (" ", i+1, ") ", p)
return
def getSharedKey(cur_serv, kdcKey, pid):
"""
pid, server, nonce
nonce, fs, shared_key, ticket
(ticket) = decoded ciphertext encrypted by kdcFS key - (session_key + pid)
make a rpc req to FS with two messages - (nonce)sharedkey.decode() and ticketcipher
Response encrypted by session_key - nonce-1
"""
print("\nNeedham-Schroeder Authentication: \n")
nonce = generate_nonce()
msg = str(pid) + " " + cur_serv + " " + nonce
channel = grpc.insecure_channel('localhost:50051')
stub = central_grpc.CentralStub(channel)
response = stub.GenKey(centralpb.Request(name = msg)).name.encode()
print("\nSTEP1: Sent a request to the KDC for a ticket to establish session between the client with pid {} and File Server {}.".format(pid, cur_serv))
fernet = Fernet(kdcKey.encode())
plaintext = fernet.decrypt(response).decode()
_, _, shared_key, ticketCipher = plaintext.split(" ")
shared_key = shared_key.encode()
fernet = Fernet(shared_key)
plaintext = nonce
ciphertext = fernet.encrypt(plaintext.encode()).decode()
print("STEP2: Session Key and Ticket received.\nSTEP3: Sent RPC request to FS with an encrypted nonce `{}` and Ticket.".format(nonce))
port = cur_serv[2:]
channel = 'localhost:' + port
channel = grpc.insecure_channel(channel)
stub = filepb_grpc.FileServerStub(channel)
response = stub.ShareKey(filepb.CPReq(file1 = ciphertext, file2 = ticketCipher)).name.encode()
plaintext = fernet.decrypt(response).decode()
if int(plaintext) + 1 == int(nonce):
print("STEP4: Received an Ecrypted nonce from FS `{}`.\nSTEP5: Sent the Encrypted nonce to FS.".format(plaintext))
print("Session has been established between client with pid {} and file server {}.\n".format(pid, cur_serv))
return shared_key
else:
print("Connection failed to establish.")
exit()
def NEW(self, request, context):
self.sessionCount += 1
fernet = Fernet(self.session[1].encode())
plaintext = fernet.decrypt(request.name.encode()).decode()
fer = Fernet(self.kdcKey)
ciphertext = fer.encrypt(
(plaintext + " " + self.session[0]).encode()).decode()
msg = "FS" + self.port + " " + ciphertext
channel = grpc.insecure_channel('localhost:50051')
stub = central_grpc.CentralStub(channel)
stub.NewFile(centralpb.Request(name=msg))
content = "File has been created by client with PID " + self.session[0]
with open(os.path.join(self.directory, plaintext), 'w') as f:
f.write(content)
print(
" {}) NEW request from Client with PID {}. Submitted the update to Central Server."
.format(self.sessionCount, self.session[0]))
ciphertext = fernet.encrypt((content).encode()).decode()
return filepb.Response(name=ciphertext)