IPsec (IP Security) is a framework used to secure IP traffic by providing confidentiality, integrity, and authentication through various protocols and algorithms. It employs encryption methods like AES and DES, hashing protocols like MD5 and SHA, and authentication techniques such as RSA digital signatures and pre-shared keys. The architecture of IPsec includes protocols like AH (Authentication Header) and ESP (Encapsulation Security Payload) for ensuring data security during transmission.

1. IPSec
By Shobhit Sharma

2. What is IPSec?
• IPSec
– stands for IP Security
– it is used for the security of general IP traffic.
• The power of IPSec lies in its ability to
– support multiple protocols and algorithms.
• It also incorporates new advancements in
– encryption and hashing protocols.

3. Objective of IPSec
The main objective of IPSec is
• to provide CIA
– (confidentiality, integrity, and authentication) for
virtual networks used in current networking
environments.

4. Objective of IPSec
• Confidentiality.
– IPSec uses encryption protocols namely AES, DES, and
3DES for providing confidentiality.
• Integrity.
– IPSec uses hashing protocols (MD5 and SHA) for providing
integrity. Hashed Message Authentication (HMAC) can
also be used for checking the data integrity.
• Authentication algorithms.
– RSA digital signatures and pre-shared keys (PSK) are two
methods used for authentication purposes.

5. Use of IPSec
• To encrypt application layer data.
• To provide security for routers sending
routing data across the public internet.
• To provide authentication without
encryption, like to authenticate that the
data originates from a known sender.

6. Use of IPSec
• To protect network data by setting up
circuits using IPsec tunneling in which
all data is being sent between the two
endpoints is encrypted, as with a Virtual
Private Network(VPN) connection.

7. Architecture of IPSec
IPSec
Policy
AH Protocol ESP Protocol
Authentication
Algorithm
Encryption
Algorithm
IPSec Domain of
Interpretation
Key Management

8. Architecture of IPSec
• IP Security Architecture
– covers the general concepts, definitions,
protocols, algorithms and security
requirements of IP Security technology.

9. Architecture of IPSec : ESP
Protocol
• Encapsulation Security Payload
– provide the confidentiality service.
• Encapsulation Security Payload is
implemented in either two ways:
– ESP with optional Authentication.
– ESP with Authentication.

10. Architecture of IPSec : ESP
Protocol
• Packet Format
Encrypted
Format
Security Parameter Index (SPI)
Sequence Number
Payload Data
Padding
Padding
Length
Next
Header
Authentication Data (Optional)

11. Architecture of IPSec : ESP
Protocol
• Packet Format
– SPI
• used to give an unique number to the connection
build between Client and Server.
– Sequence Number
• alloted to every packet so that at the receiver side
packets can be arranged properly.
– Payload Data
• the actual data or the message. It is in encrypted
format to achieve confidentiality.

12. Architecture of IPSec : ESP
Protocol
• Packet Format
– Padding
• extra bits or space added to the original message
in order to ensure confidentiality.
• it’s length is the size of added bits or space in the
original message.
– Next Header
• it means the next payload or actual data.
– Authentication Data
• optional field in ESP protocol packet format.

13. Architecture of IPSec
• Encryption Algorithm
– document that describes various encryption
algorithm used for Encapsulation Security
Payload.

14. Architecture of IPSec : AH
Protocol
• Authentication Header
– provides both Authentication and Integrity
service.
• Authentication Header is implemented in
one way only:
– Authentication along with Integrity.

15. Architecture of IPSec : AH
Protocol
• Packet Format
Security Parameter Index (SPI)
Sequence Number
Reserved
Payload
Length
Next
Header
Authentication Data (Integrity Checksum)

16. Architecture of IPSec
• Authentication Algorithm
– contains the set of the documents that
describe authentication algorithm used for
AH and for the authentication option of ESP.

17. Architecture of IPSec
• Domain of Interpretation
– the identifier which support both AH and ESP
protocols.
– It contains values needed for documentation
related to each other.

18. Architecture of IPSec
• Key Management
– contains the document that describes how
the keys are exchanged between sender and
receiver.