IPSec

IPSec

1. Authentication Header

   • Next Header
   • Payload Length
   • Reserved
   • SPI
   • Sequence Number
   • Authentication Data

2. Encapsulating Security PayLoad

   • Header
   • Payload
   • ESP Trailer
   • Authentication

3. Anti - Replay Window

   • Attacker May Gain a packet by eavesdropping
     • Using this again may pose a security risk
       • System enables the receiver to specify a window size W
         • Sequence Number are checked to see if N - W + 1, if so, message is authentic
           • Discards packet if the HMAC check fails or if the seq number is to the left of the window

4. Internet Key Exchange

   • Phase 1: Temporary SA set up
     • Phase 2: Policy Negotion
       • IPSec Protocol (AH or ESP)
         • Hashing (SHA1 or MD5)
           • Encryption Type (3DES - DES)
             • Two SA's Achieved, Keys passed to the IP Sec Driver