Machine Identity

Machine Identity
Identification and authentication of non-human computing entities
Category	Identity and security management concept
Area	Cybersecurity, digital identity and distributed systems
Core components	Identifiers, credentials, cryptographic keys, certificates and trust policies
Applications	Servers, applications, workloads, industrial devices and robots
Related concepts	Digital Identity, Public Key Infrastructure, Device authentication, Zero Trust Security
Security considerations	Credential theft, impersonation, key compromise and unauthorized access
Relevant standards	RFC 5280, IEEE 802.1AR, RFC 9846, RFC 8705

Machine identity refers to the identifiers, credentials and associated trust relationships used to identify and authenticate non-human entities in computing and communication systems. These entities may include servers, software applications, services, cloud workloads, network equipment, industrial devices and robots. The particular entity being identified depends on the architecture of the system: a physical device, an operating-system process and a network service can each have a distinct identity.

Machine identity is used in processes that establish whether a system is communicating with an expected entity and whether that entity should be permitted to access a particular resource. Such processes can rely on public-key infrastructure (PKI), cryptographic keys, digital certificates, shared secrets or identity assertions. An identifier such as a serial number or network address can distinguish one entity from another, but possession of an identifier alone does not provide cryptographic proof of identity.

Machine identity is relevant to digital identity, information security, distributed systems and machine-to-machine communication. It is not synonymous with autonomy, artificial intelligence or the safety of a physical machine. Authentication can establish that an entity possesses an expected credential, but it does not independently establish that the entity is uncompromised, that its actions are authorized or that its physical behavior is safe.

Concepts and terminology

Identification

Identification is the process of distinguishing or recognizing an entity through an identifier. Examples include device serial numbers, application names, inventory identifiers and names assigned within an organizational identity system.

An identifier may be unique within a particular system without being globally unique. Its meaning depends on the authority that assigns it and the namespace in which it is used.

For connected devices, NIST's IoT cybersecurity capability baseline identifies device identification as a fundamental capability. It distinguishes logical and physical identification from the other security capabilities required to protect a device and its operating environment.

Authentication

Authentication is the process of verifying a claim about an entity's identity using appropriate evidence.

For cryptographic authentication, evidence commonly involves demonstrating possession of a secret or private key associated with an established identity. A successful authentication exchange provides assurance subject to the security of the credential, the protocol and the underlying trust assumptions.

Authentication mechanisms may use digital signatures, message authentication codes, certificates or other protocol-specific methods.

Authorization

Authorization determines what an authenticated entity is allowed to do.

For example, a service may be authenticated successfully but still lack permission to read a particular dataset or issue a command to a robotic controller.

Authentication and authorization are distinct security functions. NIST SP 800-207 describes them as separate decisions within zero trust architectures.

Trust and identity assurance

The trustworthiness of an identity claim depends on more than the format of an identifier or certificate.

Relevant considerations include the authority that issued a credential, the procedures used to enroll the entity, the security of its private keys and the mechanisms used to validate credentials.

A technically valid certificate does not establish unlimited trust in the device or software presenting it. Its acceptance depends on the applicable trust anchors, certificate policies, validation procedures and authorization rules.

Machine identity and human digital identity

Human and machine identities share concepts such as identifiers, credentials, authentication and access control, but their operational requirements can differ.

Human digital identity systems may involve identity proofing, personal authenticators and federation between organizations. Machine identity systems often deal with devices, services or workloads that must authenticate automatically and may be created, restarted, replaced or retired without direct human involvement.

NIST SP 800-63-4 primarily addresses identity proofing, authentication and federation for users interacting with information systems. It should not be presented as a machine-identity certification standard.

Machine identity management is therefore closely related to, but not identical with, human identity and access management.

Forms of machine identity

Hardware and device identity

A physical device may have identifiers assigned during manufacturing or deployment. These can include serial numbers, network-interface identifiers and records in an asset-management system.

Such identifiers support administration and inventory management, but identifying information that can be copied is not sufficient by itself to authenticate a device securely.

Cryptographic device identity associates a device with key material that can be used in an authentication protocol.

IEEE 802.1AR specifies Secure Device Identifiers (DevIDs), including initial device identities and locally significant identities. Its framework addresses the cryptographic binding of an identity to a device and the use of such identities in provisioning and authentication.

Application and service identity

Applications and network services may require identities to authenticate themselves to other applications or services.

In a distributed application, each service can represent a separate security principal. This permits access decisions to be made using application or service identity rather than relying solely on the address of the host running the software.

NIST SP 800-207A discusses application identity infrastructure as part of zero trust access control in cloud-native and multi-cloud environments.

Workload identity

A workload is a running unit of computation, such as an application process or containerized service.

Workload identities are especially relevant to dynamic computing environments in which software instances may be frequently created, moved or replaced.

The Secure Production Identity Framework for Everyone (SPIFFE) defines standards for identifying workloads across heterogeneous environments. The framework defines structured SPIFFE identifiers and verifiable identity documents used to support workload authentication.

Identity of components within a larger system

A complex machine or robotic platform can contain several independently operating computing components.

These may include embedded controllers, networking equipment, application processes and external services. Different components may need distinct identities because their trust relationships and authorized functions differ.

This does not imply that every component must use a different credential or that every robot requires a particular identity architecture. The appropriate design depends on the system's security requirements and deployment model.

Identifiers, credentials and cryptographic mechanisms

Identifiers and namespaces

An identifier is a name or value used to designate an entity within a defined context.

Examples include an inventory record, a registered service name, a certificate subject name or a URI assigned within a workload identity system.

A trustworthy identity system must define how identifiers are assigned, interpreted and related to credentials.

An identifier alone should not be confused with a secret used to authenticate an entity.

Cryptographic keys

Cryptographic keys are used in mechanisms such as encryption, digital signatures and authentication.

In asymmetric cryptography, a private key is associated with a corresponding public key. Possession of the private key can be demonstrated through supported cryptographic operations without disclosing the key itself.

The security of this arrangement depends on suitable algorithms, correct protocol implementation and protection of the private key.

NIST SP 800-57 Part 1 Revision 5 provides guidance on key generation, protection, use, storage and other lifecycle considerations.

Digital certificates

A digital certificate associates a public key with an identity or other attributes through a digitally signed structure.

X.509 certificates are widely used in public-key infrastructures. An issuing certificate authority signs the certificate, and a relying system evaluates the certificate according to its trust and validation rules.

RFC 5280 specifies the Internet X.509 certificate and certificate revocation list profiles, including certification path validation procedures.

The presence of a certificate does not automatically prove that an entity is authorized to access a resource. Certificate validation and access-control decisions serve different purposes.

Shared secrets and tokens

Some machine-to-machine authentication systems use shared secrets, API credentials or security tokens.

These credentials differ in their security properties and verification methods. A shared secret must be protected by all parties that possess it. A bearer token generally allows an entity possessing the token to exercise the authority represented by that token, subject to the receiving system's validation rules.

OAuth 2.0 specifications include mechanisms for authenticating clients and limiting the misuse of issued access tokens. RFC 8705, for example, specifies mutual-TLS client authentication and certificate-bound access tokens.

A token or certificate should not be assumed to provide the same assurance as a hardware-bound identity merely because it identifies a non-human entity.

Machine identity lifecycle

Machine identities and their credentials require management throughout the life of the associated system.

The exact processes vary by technology and organization. Cryptographic key-management guidance, certificate enrollment specifications and device cybersecurity guidance provide established practices for handling important parts of this lifecycle.

Enrollment and provisioning

Enrollment establishes a relationship between an entity and an identity-management authority or system.

Provisioning may involve assigning identifiers, generating keys, installing credentials or recording the entity's permitted roles.

RFC 7030 specifies Enrollment over Secure Transport (EST), a protocol for certificate enrollment using secure transport and established PKI mechanisms.

Some systems can use manufacturer-provisioned device identities during initial enrollment. RFC 8995 specifies Bootstrapping Remote Secure Key Infrastructure (BRSKI), which describes a mechanism for securely bootstrapping new devices using manufacturer-installed credentials and an authorization service.

These protocols serve particular deployment models and should not be presented as mandatory components of every machine identity system.

Storage and protection

Private keys and other sensitive authentication materials require protection against unauthorized disclosure or use.

Some systems store credentials using software-controlled protection mechanisms. Others use specialized hardware designed to protect cryptographic operations and key material.

The appropriate protection depends on the expected threats, the operating environment and the consequences of credential compromise.

Renewal and rotation

Credentials may need replacement because of expiration, routine security maintenance, changes in policy or suspected compromise.

Renewal and rotation processes should maintain the required trust relationships while ensuring that obsolete credentials no longer grant access.

Key-management procedures must also account for transitions between credentials and the services depending on them.

Revocation and compromise response

If a credential is compromised or should no longer be trusted, the system may need to revoke it or otherwise prevent its further acceptance.

X.509 public-key infrastructures can use certificate revocation mechanisms and certificate validity periods. Their effectiveness depends on the validation behavior of relying systems and the mechanisms available in the deployment.

Other credential systems may require different means of invalidating access.

Retirement and ownership change

When a device, service or workload is retired, its access permissions and credentials may need to be removed or invalidated.

For equipment transferred between organizations or administrative domains, identity and trust relationships may also change.

Secure device bootstrapping specifications recognize that manufacturer-provisioned identity and the identity or trust established within an owner's local domain can have different roles.

Authentication protocols and trust architectures

Transport Layer Security

Transport Layer Security (TLS) is a protocol used to protect communications between endpoints.

TLS 1.3 supports endpoint authentication and establishment of a secure communication channel. Server authentication is part of the protocol, while client authentication is optional and depends on the deployment.

The current TLS 1.3 specification is RFC 9846, published in July 2026. It replaces RFC 8446 while retaining the TLS 1.3 protocol version.

Mutual TLS

Mutual TLS (mTLS) is a TLS configuration in which both communicating parties authenticate using suitable credentials.

It can be used for service-to-service or other machine-to-machine communication when each endpoint must authenticate the other.

The use of mTLS does not eliminate the need for application-level authorization. A system may authenticate a service successfully while denying a request that exceeds the service's permissions.

SPIFFE workload identity

SPIFFE provides identity specifications for software workloads operating in distributed environments.

A SPIFFE ID identifies a workload within a trust domain. A SPIFFE Verifiable Identity Document (SVID) communicates identity information in a form that can be validated according to the framework's rules.

The X.509-SVID specification defines how a SPIFFE identity is represented in an X.509 certificate. The SPIFFE Workload API provides mechanisms through which workloads can retrieve identity documents and associated trust information.

SPIFFE addresses workload identity and authentication. It is not a universal physical-device identity registry.

Zero trust architecture

Zero trust is a security approach in which access is not implicitly trusted because a device or service is located on a particular network or belongs to a particular organization.

NIST SP 800-207 places authentication, authorization and resource protection at the center of zero trust architectures.

NIST SP 800-207A extends this discussion to application and service identities in cloud-native environments. Machine identity therefore plays an important role in architectures that apply access-control policies to software services and devices.

Hardware identity and attestation

Cryptographic authentication and device integrity are related but distinct security concerns.

A device may possess a valid credential while executing altered or compromised software. Authentication of the credential alone does not establish the state of the complete computing platform.

Remote attestation refers to processes in which evidence about a system is evaluated to support a decision about its trustworthiness.

RFC 9334 describes the Remote ATtestation procedureS (RATS) architecture. It defines roles including the attester, verifier and relying party, and explains how evidence and attestation results can support security decisions.

Attestation is not equivalent to identification. Identity provides a way to distinguish or authenticate an entity, while attestation supplies evidence relevant to evaluating aspects of its state.

NIST SP 800-193 separately discusses mechanisms for protecting, detecting unauthorized modification of, and recovering platform firmware.

Machine identity in robotics

Robotic systems may contain embedded computers, controllers, network interfaces, perception software and services that exchange operational information.

For connected or remotely managed robotic systems, identity mechanisms can support authentication between components and access control over management interfaces, software updates and communications.

The identity of a physical robot should not automatically be treated as identical to the identity of every service or controller associated with it. Different components can have different security requirements and independently managed credentials.

Controller and device authentication

Robot controllers and associated devices may require authentication before accepting management connections or exchanging sensitive information.

Cryptographic credentials can support verification of the communicating endpoint. Authorization rules must separately determine what operations that endpoint may perform.

This distinction is particularly important in systems where commands can affect physical equipment.

Robot fleet management

A connected fleet may include devices operating under a common administrative system.

Managing access to individual machines, their software services and their credentials is one aspect of securing such an environment.

In practice, the relevant processes depend on the fleet's communications architecture, operational conditions and available management infrastructure. No single identity protocol can be assumed to apply to every robot fleet.

Industrial robotic systems

Industrial robotic equipment often operates within larger manufacturing systems containing controllers, engineering workstations and communication networks.

NIST IR 8227 documents a methodology for evaluating cybersecurity technologies in a robotic manufacturing workcell and examining their potential effects on operational performance.

The report illustrates the need to consider cybersecurity in the context of an integrated industrial system rather than treating individual credentials as sufficient protection.

Identity does not establish robot safety

A valid device certificate does not prove that a robot's control algorithms, actuators or safety functions are operating correctly.

Mechanical safety, functional safety, cybersecurity and identity assurance concern different aspects of system trustworthiness.

A robotic system may require all of these considerations, but satisfying an authentication requirement does not replace physical hazard analysis or application-specific safety engineering.

Security risks and limitations

Machine identity mechanisms address particular security problems, but their effectiveness depends on how they are implemented and managed.

Credential theft and impersonation

An attacker who obtains usable authentication credentials may be able to impersonate the corresponding service or device.

The consequences depend on the credential's authority, how it is protected and the verification performed by relying systems.

Key protection, access restrictions and appropriate compromise-response processes are therefore important elements of identity security.

Weak enrollment procedures

An identity system can be undermined if credentials are issued to an unintended entity or if the enrollment process fails to establish the required association between an entity and its credentials.

Secure enrollment mechanisms attempt to address this problem, but their effectiveness depends on the underlying trust relationships and deployment conditions.

Credential expiration and revocation

Expired, compromised or obsolete credentials can interrupt legitimate operations or create security risks if they continue to be accepted.

Systems must account for certificate validity, revocation behavior and the availability of mechanisms needed to verify credentials.

Identity and software integrity

Authentication does not necessarily detect unauthorized changes to software or firmware.

Where a security decision depends on platform state, additional mechanisms such as integrity protection or attestation may be relevant.

Interoperability and trust boundaries

Different organizations may operate separate identity systems and trust authorities.

A credential trusted within one administrative domain is not necessarily trusted in another. Cross-domain communication therefore requires explicit mechanisms for establishing the appropriate trust relationships.

SPIFFE includes specifications relating to trust domains and federation, while X.509 PKI uses certificate-path validation and trust anchors.

Standards and technical publications

Several published standards and technical specifications are relevant to machine identity. They address different aspects of identity rather than defining a single universal machine identity system.

Publication	Subject	Relevance
IEEE 802.1AR	Secure device identity	Cryptographically bound device identifiers
RFC 5280	X.509 certificate and revocation profiles	Public-key certificates and validation
RFC 7030	Enrollment over Secure Transport	Certificate enrollment
RFC 8705	OAuth mutual-TLS authentication	Client authentication and certificate-bound tokens
RFC 8995	Bootstrapping Remote Secure Key Infrastructure	Secure device enrollment and establishment of local trust
RFC 9334	Remote attestation architecture	Assessment of evidence about system state
RFC 9846	TLS 1.3	Secure communications and endpoint authentication
NIST SP 800-57 Part 1	Cryptographic key management	Key lifecycle and protection
NIST SP 800-207	Zero trust architecture	Authentication, authorization and resource access
NIST SP 800-207A	Zero trust in cloud-native systems	Application and service identity
NIST IR 8259A	IoT cybersecurity capability baseline	Device identification and related capabilities
SPIFFE specifications	Workload identity	Workload identifiers, verifiable identity documents and associated APIs

Selected books

The following books provide background on cryptography, public-key infrastructure and the engineering of secure distributed systems.

• Adams, Carlisle, and Steve Lloyd (2003). Understanding PKI: Concepts, Standards, and Deployment Considerations. 2nd edition. Addison-Wesley Professional. ISBN 978-0-672-32391-1.
• Anderson, Ross (2020). Security Engineering: A Guide to Building Dependable Distributed Systems. 3rd edition. Wiley. ISBN 978-1-119-64278-7.
• Aumasson, Jean-Philippe (2024). Serious Cryptography: A Practical Introduction to Modern Encryption. 2nd edition. No Starch Press. ISBN 978-1-7185-0384-7.

These books are supporting references on the underlying security concepts; none is presented as the source of a single universal definition of machine identity.

Further reading

• NIST SP 800-57 Part 1 Rev. 5 — Recommendation for Key Management
• NIST SP 800-207 — Zero Trust Architecture
• NIST SP 800-207A — Zero Trust for Cloud-Native Applications
• NIST IR 8259A — IoT Device Cybersecurity Capability Core Baseline
• IEEE 802.1AR-2018 — Secure Device Identity
• RFC 8995 — Bootstrapping Remote Secure Key Infrastructure
• RFC 9334 — Remote Attestation Architecture
• SPIFFE Technical Specifications

See also

• Physical AI Identity
• Digital Identity
• Robot Authentication
• Robot Cybersecurity
• Device authentication
• Public Key Infrastructure
• Zero Trust Security
• Cryptography
• Machine-to-Machine Communication
• Industrial Automation
• Internet of Things
• Autonomous Systems