3. Trust Model

この節では MATF の RFC 原文を保持し, federation trust model, metadata repository, public key pinning, JSON/JWS metadata, usage scenarios, deployments, security considerations, JSON Schema を含めます.

3.  Trust Model

   The MATF framework operates on a trust model that is central to its
   design and functionality.  This section outlines the key components
   of this trust model and its implications for federation members and
   the federation operator.

3.1.  Role of the Federation Operator

   The federation operator plays a critical role in the MATF framework.
   This entity is responsible for:

   *  Managing the central trust anchor, which is used to establish
      trust across different domains within the federation.

   *  Vetting federation members to ensure they meet the required
      standards and policies.

   *  Maintaining and securing the federation metadata, which includes
      public key pins [RFC7469], issuer certificates, and other
      essential information.

   Additionally, the federation operator SHOULD develop their own threat
   models to proactively identify potential risks and threats.  This
   process involves examining the operating environment, evaluating both
   internal and external threats, and understanding how vulnerabilities
   can be exploited.  The goal of the threat model is to enable the
   federation operator to establish mitigation strategies that address
   the identified risks.

   The security and stability of the federation rely on the integrity
   and competence of the federation operator.  Members must be able to
   fully trust this central authority, as its role is essential to
   maintaining the federation's reliability and security.

3.2.  Federation Members' Responsibilities

   Federation members share the responsibility of maintaining trust and
   security within the federation.

   Their responsibilities include:

   *  Adhering to the federation's security policies and procedures.

   *  Ensuring the accuracy and timeliness of their metadata
      submissions.

   *  Cooperating with the federation operator's vetting and security
      measures.

   By fulfilling these responsibilities, federation members help sustain
   the trust framework that enables secure and reliable communication
   within the federation.

   Federation members submit member metadata to the federation.  As part
   of federation operations, the federation MUST ensure the authenticity
   and integrity of submitted member metadata and the authenticity of
   the submitting member.

3.3.  Chain of Trust

   Each federation operates within a trust framework that encompasses
   its own security policies and procedures.  This framework is designed
   to ensure the integrity, authenticity, and confidentiality of
   communications within the federation.  Key components of this
   framework include:

   *  Public key pinning [RFC7469] and preloading to thwart on-path
      attacks by rejecting peers whose public key in the presented
      certificate does not match a pin published in the federation
      metadata.

   *  Regular updates and verification of federation metadata to prevent
      the use of outdated or compromised information.

   The federation operator aggregates, signs, and publishes the
   federation metadata, which combines all members' member metadata
   along with additional federation-specific information.  By placing
   trust in the federation and its associated federation metadata
   signature verification key, federation members trust the information
   contained within the federation metadata.

   The trust anchor for the federation is established through the
   federation metadata signature verification key, a critical component
   requiring secure distribution and verification.  To achieve this, the
   signature verification key material is distributed using a JSON Web
   Key (JWK) Set [RFC7517], providing a flexible framework for exposing
   multiple public keys, including the current signature verification
   key and keys for rollover.  This structured approach ensures members
   can readily access the necessary keys for verification purposes.

   An additional layer of security is introduced through thumbprint
   verification [RFC7638], where federation members can independently
   verify the key's authenticity.  This involves comparing the
   calculated cryptographic thumbprint of the key with a trusted value,
   ensuring its integrity.  Importantly, this verification process can
   be conducted through channels separate from the JWK Set itself,
   enhancing security by eliminating reliance on a single distribution
   mechanism.

   This trust framework is essential for enabling seamless and secure
   interoperability across different trust domains within the
   federation.

3.4.  Member Vetting

   To ensure the security and integrity of the MATF framework, a member
   vetting process is essential.  Detailed vetting processes are beyond
   the scope of this document but can be guided by established
   frameworks such as eIDAS and eduGAIN.

   The following are non-normative references to established frameworks:

   *  eIDAS: The eIDAS regulation can provide guidance for member
      vetting and identity assurance practices.

   *  eduGAIN: eduGAIN is an interfederation service connecting identity
      federations worldwide, primarily within the research and education
      sector. eduGAIN documentation on participation requirements and
      federation practices can inform member vetting processes
      [eduGAIN].

3.5.  Metadata Authenticity

   Ensuring the authenticity of metadata is necessary for maintaining
   the security and trustworthiness of the MATF framework.  This
   document specifies mechanisms for protecting and verifying the
   authenticity of federation metadata, including JWS signing.
   Operational procedures for authenticating member metadata submissions
   are outside the scope of this document and are defined by the
   federation operator or applicable regulatory bodies.