The Public Key Cryptography for Initial Authentication in Kerberos (PKINIT) protocol [RFC4556] enables the use of public key cryptography in the initial authentication exchange (that is, in the Authentication Service (AS) exchange) of the Kerberos protocol [MS-KILE]. This specification describes the Public Key Cryptography for Initial Authentication in Kerberos (PKINIT): Microsoft Extensions protocol (PKCA) and how the Windows implementation of PKINIT differs from what is specified in [RFC4556].
By using public key cryptography to protect the initial authentication, the Kerberos protocol [MS-KILE] is substantially strengthened and can be used with already existing public key authentication mechanisms such as smart cards.
This document references the PKINIT methods and data formats [RFC4556] and [RFC5349], that the client and the KDC can use both to mutually authenticate during the AS exchange with public and private key pairs and to negotiate the AS-REP key, which allows the KDC to encrypt the AS-REP key sent to the client.
Sections 1.8, 2, and 3 of this specification are normative and can contain the terms MAY, SHOULD, MUST, MUST NOT, and SHOULD NOT as defined in [RFC2119]. Sections 1.5 and 1.9 are also normative but do not contain those terms. All other sections and examples in this specification are informative.