def read_latest_intergroup_message(self, group):
"""
This is a function for a member to read the latest message that has been sent to his group from members outside his group.
Once a message has been added to a group successfully, this function must be called for every member of that group.
"""
if self.group_id != group.id:
print(bcolors.BOLD + bcolors.ERROR + "You are not a member of group ", group.id, "!! \nCannot read messages of the group!!\n" + bcolors.ENDC)
return False
if len(group.intergroup_messages) == 0:
print(bcolors.BOLD + bcolors.ERROR + "No messages have been sent to the group.\n" + bcolors.ENDC)
return False
encrypted_message = group.intergroup_messages[-1][0]
sender_id = group.intergroup_messages[-1][1]
group_polynomial = group.get_group_polynomial()
group_key = evaluate_polynomial(group_polynomial, self.secret_key)
intergroup_polynomial = decrypt_polynomial(group.intergroup_polynomial, group_key)
key = evaluate_polynomial(intergroup_polynomial, sender_id)
encoded_key = str(bin(key)[2:])
decrypted_message = decrypt(encrypted_message, encoded_key)
decoded_message = decode(decrypted_message)
print("Message read by member {}: {}\n".format(self.id, decoded_message))
self.message_history.append((decoded_message, sender_id))
return True
def request_intergroup_key(self, member_id):
"""
This function returns an inter-group key,
when a member outside the group requests for the key to send a message to the group.
"""
group_key = evaluate_polynomial(self.group_polynomial,
self.secret_keys[0])
decrypted_polynomial = decrypt_polynomial(self.intergroup_polynomial,
group_key)
intergroup_key = evaluate_polynomial(decrypted_polynomial, member_id)
print(bcolors.BOLD + bcolors.OKGREEN + "Evaluated inter group key : " +
bcolors.ENDC + str(intergroup_key))
return intergroup_key
def add_member(self, member):
"""
This function adds a new member to the group.
It generates a new group key and a new group polynomial.
"""
member_id = member.id
member_group = member.group_id
if member_group is not None:
print("\nMember {} already part of Group {}".format(
member_id, member_group))
print("\nCannot add member")
return False
print("\n****** Printing re-keying process *******")
member_key = random.randint(2**FLAGS.l, 2**FLAGS.h)
member.set_group_id(self.id)
member.set_secret_key(member_key)
self.members[member_id] = member
self.secret_keys.append(member_key)
print(bcolors.BOLD + bcolors.OKGREEN +
"\nMember {} with secret key {} added to Group {}.".format(
member_id, member_key, self.id) + bcolors.ENDC)
if (len(self.secret_keys) == 1):
print(bcolors.BOLD + bcolors.OKGREEN + "\nMaking ", member_id,
" the admin of the group: ", self.id, "\n" + bcolors.ENDC)
self.admin_id = member_id
# Generating new group polynomial and new group key
self.group_polynomial = generate_polynomial(self.secret_keys)
# Generating new intergroup polynomial
group_key = evaluate_polynomial(self.group_polynomial,
self.secret_keys[0])
intergroup_polynomial = gen_intergroup_polynomial(len(
self.secret_keys))
encrpyted_intergroup_polynomial = encrypt_polynomial(
intergroup_polynomial, group_key)
self.intergroup_polynomial = encrpyted_intergroup_polynomial
print(bcolors.BOLD + bcolors.OKGREEN +
"\nEncrypted Inter Group Polynomial : " + bcolors.ENDC +
self.intergroup_polynomial)
return True
def remove_member(self, member_id):
"""
This function removes a member with given id from the group.
It generates a new group key and a new group polynomial.
"""
if member_id not in self.members.keys():
print(bcolors.BOLD + bcolors.ERROR +
"\nMember {} is not part of Group {}".format(
member_id, self.id) + bcolors.ENDC)
print(bcolors.BOLD + bcolors.ERROR + "\nCannot remove member" +
bcolors.ENDC)
return False
if (member_id == self.admin_id):
print(bcolors.BOLD + bcolors.ERROR +
"Admin of group cannot be removed" + bcolors.ENDC)
return False
print("\n****** Printing re-keying process *******")
member = self.members.pop(member_id)
member.set_group_id(None)
self.secret_keys.remove(member.secret_key)
print(bcolors.BOLD + bcolors.OKGREEN +
"\nMember {} with secret key {} removed from Group {}.\n".format(
member_id, member.secret_key, self.id) + bcolors.ENDC)
# Generating new group polynomial and new group key
self.group_polynomial = generate_polynomial(self.secret_keys)
# Generating new intergroup polynomial
group_key = evaluate_polynomial(self.group_polynomial,
self.secret_keys[0])
intergroup_polynomial = gen_intergroup_polynomial(len(
self.secret_keys))
encrpyted_intergroup_polynomial = encrypt_polynomial(
intergroup_polynomial, group_key)
self.intergroup_polynomial = encrpyted_intergroup_polynomial
print(bcolors.BOLD + bcolors.OKGREEN +
"\nEncrypted Inter Group Polynomial : {}\n".format(
self.intergroup_polynomial) + bcolors.ENDC)
return True
def add_message_to_group(self, group, message):
"""
This is a function that handles the sending of a message by a member to the other members of the group that he is part of.
The function returns True if message was written successfully, and False otherwise.
"""
if self.group_id != group.id:
"""
Inter Group Message
"""
print("Sending inter-group message from member {} to group {}: {}\n".format(self.id, group.id, message))
key = group.request_intergroup_key(self.id)
encoded_key = str(bin(key)[2:])
encoded_message = encode(message)
encrypted_message = encrypt(encoded_message, encoded_key)
group.add_intergroup_message(encrypted_message, self.id)
print("Message has been sent to the group successfully.\n")
else:
"""
Intra Group Message
"""
print(bcolors.BOLD + bcolors.WARNING + "Sending intra-group message from member {} to group {}: {}\n".format(self.id, group.id, message) + bcolors.ENDC)
group_polynomial = group.get_group_polynomial()
group_key = evaluate_polynomial(group_polynomial, self.secret_key)
encoded_message = encode(message)
encoded_key = str(bin(group_key)[2:])
encrypted_message = encrypt(encoded_message, encoded_key)
group.add_message_to_group(encrypted_message)
print("Message has been added to the group successfully.\n")
return True