A protocol has been described about creation and use of wireless ad hoc network.

1. A Secure Protocol for
Spontaneous Wireless Ad
Hoc Networks Creation
SAHIL BAJAJ
RAGHVENDRA YADAV

2. Ad-Hoc Networks
 In Latin, ad hoc means “for this purpose only”
 An ad-hoc network is a small network, in which some of network
devices are part of the network that are part of network only for short
duration
 Peer to peer communication by use of Wi-Fi and Bluetooth technology
 Devices or nodes in the network are mobile in nature
 The wireless hosts in such networks, communicate with each other
without the existing of a fixed infrastructure and without a central
control

3. Ad Hoc Networks
Wireless Network Topology

4. Characteristics
 No Infrastructure needed
 Can be deployed quickly, where there is no wireless communication
infrastructure present
 Can act as an extension to an existing networks
 Cost effective
 Nodes are mobile and hence have dynamic network topology
 Nodes in ad hoc network play role of both router and terminal
 It is self-configuring

5. Multi hop communication
 May need to traverse multiple links to reach destination
 Mobility causes route change

6. Examples
 Classroom
 Ad hoc network between student PDAs and workstation of the
instructor
 Large IT campus
 Employees of a company moving within a large campus with PDAS,
laptops and cell phones
 Disaster response
 A mobile network as big as needed
 Vehicles
 Communicating with other vehicles for safety purpose

7. Protocol
 Creates a network which allows sharing resources and offering new
services among users
 Protocol includes all functions needed to operate without any external
support
 Provides access to information anywhere, user friendliness, and easy
deployment
 Builds a network consisting of mobile nodes that can communicate
with each other, share resources, services during a limited period of
time and in a limited space
 Have little or no dependence on a centralized administration

8.  Enables the user to have instant service without any external
infrastructure
 Services in spontaneous networks depend significantly on network
size, the nature of the participating nodes and running applications
 Tasks to be performed include: user identification, their
authorization, address assignment, and safety
 Energy constraints, node variability, and bandwidth limitations
mandate the design
 Existing methods are not enough because they need an initial
configuration (i.e., network configuration) or external authorities (for
example, central authorities)

9.  The network and protocol proposed can establish a secure self-configured
environment for distribution of data and sharing of resources and services
among users.
 A user is able to join the network because he/she knows someone that
belongs to it, and hence in this way the certification authority is distributed
between the users that trust the new user
 The network management is also distributed, which allows the network to
have a distributed name service
 A mechanism is suggested which allows nodes to check the authenticity of
their IP addresses while not generating duplicated IP addresses.
 Asymmetric cryptography is applied for device identification , where each
device has a public-private key pair and symmetric cryptography to exchange
session keys between nodes

10. Secure Spontaneous Network
 Network members and services may vary because devices are free to
join or leave the network
 Steps for the creation of a network
 1. Joining Procedure
 2. Services Discovery
 3. Establishing trusted chain and changing trust level

11. Joining Procedure
 System is based on the use of an IDentity Card (IDC) and a certificate
 IDC contains public and private components
 Public component contains a Logical Identity (LID), which is unique for
each user and allows nodes to identify it
 LID includes information such as name, photograph, user’s public key (Ki),
the creation and expiration dates, an IP proposed by the user, and the
user signature
 The user signature is generated using the Secure Hash Algorithm (SHA-1)
on the previous data to obtain the data summary
 Data summary is signed with the user’s private key
 Private component contains the private key (ki)

12.  Certificate Cij of the user i consists of a validated IDC, signed
by a user j that gives its validity
 No central certification authority is used to validate IDC
 The certification authority for a node could be any of the trusted
nodes
 All nodes can be both clients and servers, can request or serve
requests for information or authentication of other nodes
 The first node creates the spontaneous network and generates
a random session key, which will be exchanged with new nodes
after the authentication phase

13.  When node B wants to join an existing network, it must choose a node
within communication range to authenticate with(e.g., node A)
 A will send its public key
 Then, B will send its IDC signed by A’s public key
 Next, A validates the received data
 Finally, A will send its IDC data to B
 This data will be signed by B’s public key will validate A’s IDC and will
establish the trust
 If A does not reply to the joining request, B must select another
network node (if one exists)

14.  Symmetric key is used as a session key to cipher the confidential
messages between trust nodes
 It has less energy requirements than the asymmetric key
 The asymmetric key encryption scheme is used for distribution of the
session key and for the user authentication process

15. Services discovery
 A user can ask other devices in order to know the available services.
 It has an agreement to allow access to its services and to access the
services offered by other nodes
 The fault tolerance of the network has to be maintained
 Services provided by B are available only if there is a path to B, and
disappear when B leaves the network

16. Establishing trusted chain and changing
trust level
 There are only two trust levels
 Node A either trusts node B
 Node A does not trust node B.
 If node A do not establish trust level with node B directly, it can be
established through trusted chains
 If A trusts C and C trusts B, then A may trust B
 Trust relationship can be asymmetric
 Trust level can change over time
 Node A may decide not to trust node B although A still trusts C and C trusts B
 It can also stop trusting if it discovers that previous trust chain does not exist
anymore

17. Protocol and Network Management
 Avoids the need for a central server, making the tasks of building the
network and adding new members very easy
 Each node is identified by an IP address
 Services are shared using TCP connections
 Short-range technology (Bluetooth) is used to allow authentication of
nodes when they join the network
 After the authentication process, each node learns the public
information about other nodes

18.  Depending on the type of service, each node requests the services
 From all the nodes that it trusts
 From all nodes in the network
 Request to multiple nodes is made through diffusion processes
 Protocol prioritizes access to information through trusted nodes
 When the information cannot be obtained through these nodes, it can
then ask other nodes
 Nodes may request information from other nodes
 The node replying to this request must sign this data ensuring the
authenticity

19. Network Creation
 The first node in the network will be responsible for setting the global
settings of the spontaneous network (SSID, session key, ...)
 Each node must configure its own data (including the first node) such
as IP, port, user data
 This information will allow the node to become part of the network
 After this data are set in the first node, it changes to standby mode
 The second node first configures its user data

20.  Then, the greeting process starts
 Find a device that will give trust to it
 The node that belongs to the network, and is responsible for validating
the new node’s data, will perform a diffusion process
 These nodes will forward the received packets to their neighbours until
the data reach all nodes in the network
 This process verifies uniqueness of the new node’s data
 It authenticates against the first node
 Each additional node authenticates with any node in the network

21. Illustration
 Steps for authentication of new device B
 The receiver node A validates the received data
 It then sends a broadcast message to check if these data are not used in
the network (even the IP address)
 This IP checking packet is sent randomly to all devices
 When the authentication device receives the IP checking reply, it sends
the authentication reply to the new device
 If any step is wrong, an error message is sent to the new device
 When the node is authenticated, it is able to perform several tasks

22. Tasks performed by authenticated node
 The authenticated node can perform the following tasks
 Display nodes
 Modify trust of nodes
 Update the information
• Allows a node to learn about other nodes in the network
• update could be for only one user or for all users in the network
 Process an authentication request
• Reply to an information request requested information will be sent directly to
the requesting node or routed if the node is not on the communication range

23.  Forward an information request
• The request will be forwarded if it is a broadcast message
 Send data to one node
• It can be sent symmetrically or asymmetrically encrypted, or unencrypted
 Send data to all nodes
• Done by flooding system
• It can be sent symmetrically encrypted or unencrypted
 Leave the network

24. Protocol Implementation
 Developed 16 packets for the proper running of the protocol
 To join a spontaneous network start the process by sending a
Discovery request packet (01)
 Contains the Logical IDentity of the user in order to let the destinations know the
sender device
 Receivers will reply with the Discovery reply packet (02)
 Contains Logical Identity and their IP address
 Authentication request packet (03) - used for the new device
authentication

25.  Authentication reply packet (04) - confirms that the proposed IP and
the email are unique, so the new device is authenticated
 In case of duplication - error packet sent
 IP and e-mail checking packet (05) – used by the authenticator device
 verifies that no one in the network has the same email or IP address as
the one proposed by the new device
 IP and e-mail checking reply packet (06) - sent to authenticator
device
 verify that the IP and e-mail are unique

26.  If IP is duplicated, device must restart the authentication process
after the generation of a new IP
 Update request to one node (07) - to request information to a specific
known node
 Update reply from one node (08) - to reply with information
requested by update request packet to one node
 Update request to all network nodes packet(09) – request made from
all nodes in the network, by flooding
 Update reply to all network nodes packet (10) - reply with the
information requested

27.  Certificate request to trusted nodes (11) - request the certificate
from all trusted nodes
 Certificate request to known nodes (12) - request the certificate from
all known nodes
 Certificate reply packet (13) – Reply to above two packets
 Data are sent using the Packet for sending data (14)
 Error packet (15) - to indicate that this operation is not possible
 Authentication has failed
 Node does not have the required data
 Acknowledge packet(16) - to confirm to sender that the packet has
arrived at its destination correctly

28. ID Packet Name Description
01 P_DISCOVERY Discovery request
02 R_DISCOVERY Discovery reply
03 P_AUTHENT Authentication request
04 R_AUTHENT Authentication reply
05 P_IP IP and Email checking
06 R_IP Ip and Email checking reply
07 P_ACTUALIZA Update request to one node
08 R_ACTUALIZA Update request from one node
09 P_BROADCAST Update request to all network node
10 R_BROADCAST Update reply to all network node
11 P_NODO_CONF Certificate request to trusted node
12 P_NODO Certificate request to known node
13 R_NODO Certificate reply
14 P_DATOS Packet for sending data
15
16
P_ERROR
P_ACK
Error
Acknowledge

29. Session Key Revocation
 Session key has an expiration time, so it is revoked periodically
 A node that leaves the spontaneous network will keep the session key
until it expires
 It will let the user return to the network if it has joined previously(the
spontaneous network is usually set up for a limited period of time)
 However, if a node is disconnected from the network during the
period of time when the session key has been renewed, it will not be
able to access the network until it is authenticated again with
someone from the network

30. PERFORMANCE ANALYSIS
 Java programming
 Protocol may work on devices with limited resources, Java 2 Platform,
Micro Edition (J2ME) is used
 Also has a small and fast virtual machine (KVM) that allows us to run
the software without overloading the device
 Devices must have a minimum of 160 KB memory to store theJava
technology stack
 It can run when there are computing and process limitations, and for
low-power devices
 Allows the implementation of communication protocols over both
WiFi and Bluetooth technologies

31. CONCLUSION
 We show the design of a protocol that allows the creation and
management of a spontaneous wireless ad hoc network
 A user without advanced technical knowledge can set up and
participate in a spontaneous network
 Storage and volatile memory needs are quite low and the protocol can
be used in regular resource-constrained devices (cell phones, PDAs...)

32. References
 [1].Raquel Lacuesta, Jaime Lloret, Miguel Garcia, Lourdes Pen ˜alver , “A
Secure Protocol for Spontaneous Wireless Ad Hoc Networks Creation” IEEE
TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS, VOL. 24, NO. 4,
APRIL 2013
 [2]. https://en.wikipedia.org/wiki/Wireless_ad_hoc_network
 [3]. https://www.youtube.com/watch?v=Jmfd4KPGPp0
 [4]. http://www.cs.jhu.edu/~cs647/intro_adhoc.pdf