Many covert channels could be generated by using different IP header fields to introduce data hiding schemes. This paper presents the scheme and the description of a new suggested steganographic method for data hiding in the IP ID field.
In the suggested method; an appropriate encryption algorithm and key could be used to encrypt the plaintext character so the ciphertext value could be presented in the form of the 8-bit binary representation and then could be embedded within the IP ID field using a new suggested embedding algorithm that uses pre-agreed key and direction. The method may be applied with either IPv4 or IPv6 packets. With IPv6; IP packet fragmentation is required by the packet source. In this method; the packet source should be the steganogram sender. The method has the advantages of being resistant to packet filtering and stateful inspection firewalls and it could be applied through different network scales and characteristics. To provide more confidentiality to the hidden data in the IP ID field; the paper suggests implementing the IPsec encryption in the tunnel mode between the steganogram sending and receiving gateways.