Secure IP access protocol framework and supporting network architecture
A protocol framework for a Secure IP Access (SIA) method, and supporting components deployed on IP hosts and IP networks. Using this method, an IP host can establish a secure data channel within an IP network over an insecure shared link while requesting IP address and networking configuration parameters from the IP network. A system administrator can implement strong access control against various attacks that an edge IP network may have to face, such as a denial-of-service attack that exhausts assignable IP addresses. This is a lightweight, scalable, and backward-compatible solution that can improve security performance for public and corporate LANs having open access such as wireless access points and Ethernet jacks.
1. A method for a mobile wireless IP host to authenticate to an IP network, comprising:
broadcasting a dynamic host configuration protocol (DHCP)_DISCOVERY message including a HOST_HELLO message that specifies a plurality of cryptography options for the IP network including a host-to-network authentication method, network-to-host authentication method, key exchange algorithm, and encryption algorithm, wherein the DHCP_DISCOVERY message is transmitted from the mobile wireless IP host over a wireless interface to an access point;
after broadcasting the dynamic host configuration protocol (DHCP)_DISCOVERY message, receiving a DHCP_OFFER message including an option confirming the plurality of cryptography options when the plurality of cryptography options meet security requirements of the IP network, wherein the DHCP_OFFER message does not allocate an IP address to the mobile wireless IP host, wherein the DHCP_OFFER message is received at the mobile wireless IP host over the wireless interface from the access point;
after broadcasting the dynamic host configuration protocol (DHCP)_DISCOVERY message and after receiving the DHCP_OFFER message, sending a DHCP_REQUEST message including authentication credentials responsive to receiving the DHCP_OFFER, wherein the DHCP_REQUEST message is sent from the mobile wireless IP host over the wireless interface to the access point; and
after sending the DHCP_REQUEST message, receiving a DHCP_ACK message when the mobile wireless IP host is authenticated by the network, the DHCP_ACK message including a NETWORK_CONFIG option with encrypted network configuration parameters, wherein the DHCP_ACK message is received at the mobile wireless IP host over the wireless interface from the access point.
2. The method recited in claim 1 , wherein the DHCP_OFFER message includes a NETWORK_AUTH option containing a challenge number A and a Diffie-Helman (D-H) key exchange triplet <g, P, X>, where, X=g x mod P; x is a random secret generated by a secure IP access server on the network; g is a generator; P is a prime number yielding P=2Q+1; and Q is a prime number.
3. The method recited in claim 2 , wherein the DHCP_REQUEST message includes a HOST_AUTH option including at least one of an IP host identifier, a challenge number B, and a D-H key exchange parameter Y, where Y=g y mod P and y is a random secret generated by the mobile wireless IP host.
4. The method recited in claim 3 , further comprising calculating a session key K=X y mod P.
5. The method recited in claim 3 , wherein the DHCP_ACK message includes a NETWORK_AUTH option comprising B∥Es(B), where B is enciphered with a secret key.
6. The method recited in claim 5 , further comprising:
determining whether the challenge B matches the response Es(B); and
when the challenge B matches the response ES(B), sending the network a DHCP_INFORM message with a HOST_FINISH option comprising text enciphered with the session key K.
7. The method recited in claim 3 , wherein the DHCP_ACK message includes a NETWORK_FINISH option comprising text enciphered with a session key K=Y x mod P calculated by an authentication server on the IP network.
8. The method recited in claim 3 , wherein the NETWORK_CONFIG option with the network configuration parameters comprises an assigned IP address, subnet mask, and default gateway router IP address, wherein at least the assigned IP address is enciphered with a session key K=Y x mod P.
9. The method recited in claim 1 wherein the DHCP_OFFER message includes a key exchange triplet, and wherein the DHCP_REQUEST message includes a key exchange parameter.
10. A method of authenticating a mobile wireless IP host in an IP network, comprising:
receiving a broadcast dynamic host configuration protocol (DHCP)_DISCOVERY message including a HOST_HELLO message that specifies a plurality of cryptography options for the IP network including a host-to-network authentication method, network-to-host authentication method, key exchange algorithm, and encryption algorithm, wherein the DHCP_DISCOVERY message is received from the mobile wireless IP host over a wireless interface at an access point of the IP network;
responsive to receiving the dynamic host configuration protocol (DHCP)_DISCOVERY message, transmitting a DHCP_OFFER message including an option confirming the plurality of cryptography options when the plurality of cryptography options meet security requirements of the IP network, wherein the DHCP_OFFER message does not allocate an IP address to the mobile wireless IP host, wherein the DHCP_OFFER message is transmitted to the mobile wireless IP host over the wireless interface from the access point of the IP network;
after receiving the dynamic host configuration protocol (DHCP)_DISCOVERY message and after transmitting the DHCP_OFFER message, receiving a DHCP_REQUEST message including authentication credentials responsive to the DHCP_OFFER, wherein the DHCP_REQUEST message is received from the mobile wireless IP host over the wireless interface at the access point of the IP network;
responsive to receiving the DHCP_REQUEST message, authenticating the mobile wireless IP host; and
responsive to authenticating the mobile wireless IP host, transmitting a DHCP_ACK message, the DHCP_ACK message including a NETWORK_CONFIG option with encrypted network configuration parameters, wherein the DHCP_ACK message is transmitted to the mobile wireless IP host over the wireless interface from the access point of the IP network.
11. The method recited in claim 10 , wherein the DHCP_OFFER message includes a NETWORK_AUTH option containing a challenge number A and a Diffie-Helman (D-H) key exchange triplet <g, P, X>, where, X=g x mod P; x is a random secret generated by a secure IP access server on the network; g is a generator; P is a prime number yielding P=2Q+1; and Q is a prime number.
12. The method recited in claim 11 , wherein the DHCP_REQUEST message includes a HOST_AUTH option including at least one of an IP host identifier, a challenge number B, and a D-H key exchange parameter Y, where Y=g y mod P and y is a random secret generated by the mobile wireless IP host.
13. The method recited in claim 12 , further comprising calculating a session key K=X y mod P.
14. The method recited in claim 12 , wherein the DHCP_ACK message includes a NETWORK_AUTH option comprising B∥Es(B), where B is enciphered with a secret key.
15. The method recited in claim 14 , further comprising:
when the challenge B matches the response ES(B), receiving a DHCP_INFORM message with a HOST_FINISH option comprising text enciphered with the session key K, wherein the DHCP_INFORM message is received at the access point of the wireless network.
16. The method recited in claim 12 , wherein the DHCP_ACK message includes a NETWORK_FINISH option comprising text enciphered with a session key K=Y x mod P calculated by an authentication server on the IP network.
17. The method recited in claim 12 , further comprising:
after receiving the DHCP_DISCOVERY message and after receiving the DHCP_REQUEST message, assigning an IP address for the mobile wireless IP host responsive to authenticating the mobile wireless IP host, wherein the NETWORK_CONFIG option with the network configuration parameters comprises the assigned IP address, subnet mask, and default gateway router IP address, wherein at least the assigned IP address is enciphered with a session key K=Y x mod P.
18. The method recited in claim 10 wherein the DHCP_OFFER message includes a key exchange triplet, and wherein the DHCP_REQUEST message includes a key exchange parameter.