Machine identity is the digital identity assigned to non-human entities (servers, applications, services, workloads, devices, containers, and increasingly AI agents) used to authenticate and authorize them as they communicate and access resources. Machine identities now vastly outnumber human ones in most organizations, and managing and securing them has become a major, fast-growing challenge.

Just as humans need identities to access systems, so do machines, and modern computing involves an enormous and expanding population of them, each needing to prove who it is and what it’s allowed to do.

How machine identities work

Machines authenticate not with passwords or biometrics but with credentials suited to automation: cryptographic keys, digital certificates (like TLS certificates), API keys, and tokens. A service proving its identity to another service, a workload accessing a database, or a device connecting to a cloud all rely on machine identities and their credentials. These credentials establish trust between machines without human involvement.

Why machine identity is a growing challenge

The scale and nature of machine identities create real risks. There are far more of them than human identities, and they proliferate rapidly in cloud-native, microservices, and automated environments. Their credentials (keys, certificates, secrets) can be leaked, hard-coded, over-permissioned, or left to expire unexpectedly, causing outages or breaches. Unlike employees, machines don’t have an HR-driven lifecycle, so provisioning and deprovisioning them cleanly is harder, and orphaned or over-privileged machine identities are a favorite attack vector. Compromising a machine identity with broad access can be as damaging as compromising an admin account.

The machine identity lifecycle

Machine identities have a lifecycle (creation, credential issuance and rotation, permission management, and decommissioning) that must be managed, often at large scale and high velocity. Poor management (long-lived credentials, no rotation, excessive permissions, no visibility) is where the risk concentrates. Best practices include short-lived credentials, automated rotation, least-privilege scoping, strong secrets management, and visibility into all machine identities and what they can access.

Machine identity and AI agents

The rise of AI agents adds a consequential new class of machine identity. An AI agent acting on a user’s behalf needs its own identity, must be authenticated, and should be granted tightly-scoped, often ephemeral authority, exactly the least-privilege, just-in-time approach that good machine-identity management calls for. As autonomous agents proliferate, treating them as machine identities that need proper authentication, authorization, and lifecycle management (rather than unmanaged automation) becomes critical. Machine identity, once a back-office infrastructure concern, is moving to the center of security as non-human actors multiply.

Frequently asked questions

What is machine identity?

The digital identity of non-human entities (servers, services, workloads, devices, and AI agents) used to authenticate and authorize them.

How do machines authenticate?

With cryptographic keys, digital certificates, API keys, and tokens rather than passwords or biometrics.

Why is machine identity a security challenge?

Machine identities vastly outnumber humans, proliferate fast, and their credentials can be leaked, over-permissioned, or poorly managed.

How does machine identity relate to AI agents?

AI agents are a new class of machine identity needing authentication and tightly-scoped, just-in-time authorization.

How should machine credentials be managed?

With short-lived credentials, automated rotation, least-privilege scoping, strong secrets management, and full visibility into what each can access.

Why do machine identities outnumber human ones?

Cloud-native systems, microservices, and automation create many services and workloads per human, each needing its own identity, a gap that widens with AI agents.

Related: Non-Human Identity (NHI) · AI Agents / Agentic AI · Principle of Least Privilege · Fine-Grained Authorization (FGA) · IAM