1.7 Versioning and Capability Negotiation

  • Article

This document covers versioning in the following areas:

  • Protocol versions: The protocol version is part of the Internet Security Association and Key Management Protocol (ISAKMP) header as specified in [RFC2408] section 3.1. Both IKE and the Authenticated Internet Protocol use version 1.0.

  • Exchange modes and authentication: The Authenticated Internet Protocol supports the following varieties of anonymous, one-way, and mutual authentications, which depend on the exchange mode that is in use (either main mode or extended mode).

    Exchange mode

    Authentication modes

    Main mode (MM)

    Anonymous, one-way, and mutual

    Extended mode (EM)

    One-way and mutual

    Extended mode (EM) does not support an anonymous authentication option because an anonymous authentication in EM would be the same as EM authentication not performing at all. In MM, anonymous authentication mode is accompanied by a Diffie-Hellman exchange.

    The following authentication methods are supported. See section 2.2.3.4 for details on the corresponding values for each authentication method.

    Authentication method

    Options

    Anonymous

    No authentication.

    Kerberos [RFC4120]

    Mutual authentication only.

    NTLM [MS-NLMP]

    One-way authentication only (client authentication).

    TLS [RFC3546]

    One-way or mutual authentication. If one-way, always server authentication.

  • Cryptographic parameters: These parameters are negotiated in different phases of the protocol (main mode and quick mode). The algorithm and parameter numbers are specified in [IANAIPSEC] and [IANAISAKMP]. The vendor can implement any cryptographic algorithms.<2>

  • Capability negotiation: Similar to IKE, the Authenticated Internet Protocol can advertise specific capabilities through Vendor ID payloads as specified in [RFC2408] section 3.16.<3>

    Vendors can create unique vendor IDs for their specific implementation.<4>

  • IKEv1 coexistence: When the initiator supports both IKEv1 and the Authenticated Internet Protocol, the initiator determines which protocol to use in negotiating SAs that are based on the capabilities of its remote peer. See section 3.2 for more information.