MPAI-PTF V1.0 – Architecture

Technical Specification: Process Instance Trust Framework (MPAI-PTF) V1.0 defines the architectural components and trust relationships enabling Process Instances to establish trust in distributed and zero‑trust environments. The Architecture specifies the roles, data structures, and interactions required for a Process Instance to present verifiable identity, credentials, and evidence, and for another Process Instance to evaluate these elements against a Policy Binding to derive a Trust Decision.

The PTF Architecture is composed of the following elements:

Element	Definition
Process Instance	An AI Module (per the MPAI-AIF standard) or a Process (per the MMM-TEC standard) that participates in trust establishment by presenting its Cryptographic Instance Identity, Instance Credential, and Attestation Evidence. A Process Instance may request trust from another Process Instance or evaluate trust requests it receives.
Cryptographic Instance Identity	A structured representation of the cryptographic identity of a Process Instance. The CII includes the public key and associated metadata required to verify signatures and bind the identity to an Instance Credential.
Instance Credential	A signed object binding a Process Instance’s Cryptographics Instance Identity to a Trust Anchor. The Instance Credential asserts the validity of the identity and may include attributes relevant to trust evaluation.
Trust Anchor	An entity whose public key is trusted to issue or validate Instance Credentials. Trust Anchors form the root of trust in PTF and may be managed by governance processes external to this Technical Specification.
Attestation Evidence	Information describing the state, configuration, or behaviour of a Process Instance. Evidence Items are typed according to the Security Evidence Taxonomy and may be signed or unsigned. Evidence supports the evaluation of trust policies.
Policy Binding	A structured set of requirements defining the trust conditions that a Process Instance must satisfy. A Policy Binding may specify required Trust Anchors, cryptographic algorithms, evidence types, attributes, and validity constraints.
Trust Protocol	The set of messages and procedures enabling Process Instances to exchange identity, credentials, evidence, and trust decisions. The Trust Protocol defines the TrustRequest and TrustResponse messages and the rules governing their use.
Verification Pipeline	The ordered set of procedures applied to a TrustRequest to derive a Trust Decision. The Verification Pipeline includes schema validation, credential verification, evidence verification, and policy evaluation.

Trust Establishment Model

Trust establishment in PTF follows a request–response model:

1. A Trust Anchor provides the means to negotiate Trust in a service-oriented Request/Response paradigm.
2. A Requester Process Instance creates a TrustRequest containing its Cryptographic Instance Identity, Instance Credential, and Attestation Evidence.
3. The Requester Process Instance sends the TrustRequest to its Trust Anchor.
4. Trust Anchor makes the TrustRequest Trusted.
5. The Requester Process Instance sends the TrustedRequest to a ResponderProcess Instance .
6. The Responder Process Instance sends the Trusted Request to its Trust Anchor.
7. Trust Anchor informs the Responder of the Trust worthiness of the received TrustedRequest.
8. The Responder prepares a TrustResponse indicating acceptance, rejection, or conditional trust, optionally including its own identity and credentials.
9. The Responder sends its prepared TrustResponse to its Trust Anchor.
10. The Trust Anchor applies the Verification Pipeline to the received TrustResponse.
11. The Trust Anchor sends the verified Trust Response to Responder.
12. Responder issues a TrustResponse indicating.

This model supports:

• Out-of-band trust establishment.
• Mutual authentication, authentication, and acceptance (Triple A), where both parties independently evaluate each other.
• Policy‑driven negotiation, where trust depends on satisfying specific requirements.

Distributed and Zero‑Trust Operation

The PTF Architecture supports operation in:

• Local environments, where Process Instances execute on the same platform.
• Distributed environments, where Process Instances communicate across networks.
• Full-Trust Environments, (see definition).

In all cases, trust must be established through verification of identity, credentials, evidence, and policy.

Interoperability

The Architecture enables interoperability across independent implementations by standardising:

• Identity representation
• Credential structure
• Evidence types
• Policy requirements
• Trust Protocol messages
• Verification procedures

Implementations may differ internally but must conform to the normative structures and procedures defined in this Technical Specification.

2. Actors

Actor	Definition
Requester Process Instance	A Process Instance that initiates trust establishment by sending a TrustRequest containing its identity, credentials, and evidence.
Responder Process Instance	A Process Instance that receives a TrustRequest and applies its Verification Pipeline to derive a Trust Decision.
Trust Anchor	An entity that converts – A TrustRequest into a Trusted Request and informs of the trust-worthiness of a received TrustRequest exchanging Credentials resulting from out-of-band trust negotiation. – A TrustResposeinto a Trusted Response and informs of the trust-worthiness of a received TrustResponse exchanging Credentials resulting from out-of-band trust negotiation.
Evidence Provider	A component or service that generates Attestation Evidence describing the state or behaviour of a Process Instance.
Policy Authority	An entity that defines or manages Policy Bindings used by Process Instances to evaluate trust.