IKE Overview

The Internet Key Exchange (IKE) daemon, in.iked(1M), negotiates and authenticates keying material for security associations in a protected manner. The daemon uses random seeds for keys from internal functions provided by the SunOS^TM. IKE provides Perfect Forward Secrecy (PFS). In PFS, the keys that protect data transmission are not used to derive additional keys. Also, seeds used to create data transmission keys are not reused.

When the IKE daemon discovers a remote host's public encryption key, the local system can then use that key. The system encrypts messages by using the remote host's public key. The messages can be read only by that remote host. The IKE daemon performs its job in two phases. The phases are called exchanges.

Phase 1 Exchange

The Phase 1 exchange is known as Main Mode. In the Phase 1 exchange, IKE uses public-key encryption methods to authenticate itself with peer IKE entities. The result is an ISAKMP (Internet Security Association and Key Management Protocol) Security Association. An ISAKMP security association is a secure channel for IKE to negotiate keying material for the IP datagrams. Unlike IPsec SAs, the ISAKMP security associations are bidirectional, so only one security association is needed.

How IKE negotiates keying material in the Phase 1 exchange is configurable. IKE reads the configuration information from the /etc/inet/ike/config file. Configuration information includes the interfaces that are affected, the algorithms that are used, the authentication method, and if PFS is used. The two authentication methods are pre-shared keys and public key certificates. The public key certificates can be self-signed, or the certificates can be issued by a Certificate Authority (CA) from a PKI (Public Key Infrastructure) organization. Organizations include Sun^TM Open Net Environment (Sun ONE) Certificate Server, Entrust, and Verisign.

Phase 2 Exchange

The Phase 2 exchange is known as Quick Mode. In the Phase 2 exchange, IKE creates and manages the IPsec SAs between hosts that are running the IKE daemon. IKE uses the secure channel that was created in Phase 1 to protect the transmission of keying material. The IKE daemon creates the keys from a random number generator by using the /dev/random. The daemon refreshes the keys at a configurable rate. The keying material is available to algorithms that are specified in the configuration file for IPsec policy.