Internet Key Exchange (IKE)

Internet Key Exchange (IKE) is a protocol that supports the formation of a security association (SA) under IPSec. IKE incorporates a variety of frameworks, protocols, and techniques into a hybrid system that allows for the confidential formation of a shared secret at each end of a tunnel. Some of the technologies incorporated into IKE include:

• Internet Security Association and Key Management Protocol (ISAKMP)
• Oakley
• SKEME
• X.509
• Diffie-Hellman key exchange

ISAKMP is framework for security key exchange. Oakley and SKEME are two different key exchange methods, that are combined in IKE. X.509 certificates are used to authenticate each end of tunnel. Diffie-Helman allows for the shared secret to formed without cleartext key transmission.

See: RFC 4306

References:

http://www.cisco.com/en/US/docs/ios/11_3/feature/guide/isakmp.html

http://www.networksorcery.com/enp/protocol/ike.htm

http://www.tcpipguide.com/free/t_IPSecKeyExchangeIKE.htm