A non-human identity (NHI) is any digital identity that belongs to a machine or workload rather than a person, including service accounts, API keys, tokens, SSH keys, certificates, and the identities of applications, devices, and AI agents.
Non-human identities authenticate software to software: services, scripts, containers, devices, and AI agents. They now vastly outnumber human identities in most organizations. Because they often rely on long-lived secrets like API keys and SSH keys that are rarely rotated, NHIs are a growing attack surface. Securing them means inventory, strong credentials, rotation, and least privilege.
Key Takeaways
- An NHI is a machine or workload identity: service accounts, API keys, tokens, certificates, SSH keys, and AI agents.
- NHIs typically outnumber human identities by a large factor and are growing with cloud, DevOps, and AI.
- They often depend on long-lived, poorly tracked secrets, which makes them a common breach vector.
- Securing NHIs requires a complete inventory, strong and short-lived credentials, rotation, and least privilege.
- Certificates and managed keys give NHIs stronger, more auditable identities than static secrets.
What is a Non-Human Identity?
A non-human identity is a digital identity used by software rather than a person. When one service authenticates to another, when a script calls an API, or when a device connects to a network, it uses a non-human identity. These identities are the connective tissue of modern systems, and they need the same rigor applied to human accounts: strong credentials, least privilege, and auditing.
Types of Non-Human Identities
Non-human identities take many forms across an environment.
| Type | What It Identifies |
|---|---|
| Service accounts | One application or service authenticating to another. |
| API keys and tokens | Scripts and integrations calling APIs. |
| Certificates | Servers, clients, and devices in TLS and mTLS. |
| SSH keys | Automated and administrative access to systems. |
| Workload identities | Containers, serverless functions, and cloud workloads. |
| AI agents | Autonomous software acting on a user’s behalf, usually built on a workload identity with delegated, scoped tokens. |
Why NHIs Are a Growing Risk
Non-human identities are attractive targets because they are numerous, powerful, and often poorly tracked. It helps to separate two kinds of credential here: static secrets such as API keys and long-lived tokens, which carry no built-in expiry and are easy to copy, and cryptographic credentials such as certificates and short-lived tokens, which can be bound to an identity and expired on a schedule. Most NHI risk comes from the first kind. Static secrets get hard-coded into source code, copied between systems, and almost never rotated. Most organizations cannot produce a complete list of their machine identities, so a leaked credential can give an attacker durable, low-visibility access. As cloud, DevOps, and AI expand, both the number of NHIs and the size of this attack surface keep rising.
NHI vs Human Identity
| Human identity | Non-human identity | |
|---|---|---|
| Belongs to | A person | Software, a workload, or a device |
| Authenticated with | Password, MFA, biometrics | Keys, certificates, tokens, secrets |
| Count | One per person | Many per person, often thousands total |
| Lifecycle | Relatively stable | Created and destroyed rapidly |
How to Secure Non-Human Identities
Securing NHIs follows a clear sequence:
- Inventory every non-human identity and the credentials it uses.
- Replace static secrets with cryptographic credentials such as certificates and short-lived tokens. The strength comes from bounded validity and automated issuance, not the format alone, so pair them with automated lifecycle management.
- Rotate credentials automatically so none are long-lived.
- Enforce least privilege so each identity can do only what its function requires.
- Monitor and audit usage to detect anomalous or unauthorized access.
NHIs and Machine Identity Management
Cryptographic credentials give non-human identities a stronger, more auditable foundation than static secrets. This is the domain of machine identity management: issuing and tracking certificates, and managing HSM- or KMS-backed keys under a defined lifecycle, spanning SSH keys and certificates across services, devices, and agents.
How Encryption Consulting helps
Encryption Consulting helps organizations bring non-human identities under control. SSH Secure manages the SSH key lifecycle, and CertSecure Manager gives services, devices, and agents certificate-based identities you can inventory, rotate, and revoke, backed by ISO/IEC 27001:2022 and SOC 2 certified practices.
Frequently Asked Questions
What Is an Example of a Non-Human Identity?
Examples include a service account that lets one application talk to another, an API key used by a script, a TLS or client certificate identifying a server or device, an SSH key used for automated access, a cloud workload identity, and the identity of an AI agent. Any credential that authenticates software rather than a person is a non-human identity.
Why Do Non-Human Identities Outnumber Humans?
Modern systems are built from many small, automated parts. Microservices, containers, serverless functions, CI/CD pipelines, devices, and now AI agents each need an identity to authenticate to other services. Every human user is supported by many machine identities, so NHIs typically outnumber human identities by a large factor, and the gap grows with cloud and AI adoption.
How Are NHIs Different From Human Identities?
Human identities belong to people and are protected with passwords, MFA, and human-oriented controls. Non-human identities belong to software and often rely on keys, certificates, or tokens with no human present to approve access. NHIs can be created and destroyed rapidly, exist in huge numbers, and frequently use long-lived secrets, which makes inventory and rotation harder.
What Is the Biggest Risk With Non-Human Identities?
The biggest risk is unmanaged, long-lived secrets. API keys and other credentials are often hard-coded, shared, and rarely rotated, and many organizations lack a full inventory of them. An exposed NHI secret can give an attacker persistent, hard-to-detect access. Strong, short-lived credentials and complete visibility are the main defenses.
How Do You Secure Non-Human Identities?
Start with a complete inventory of every NHI and its credentials. Replace static secrets with strong, short-lived credentials such as certificates and tokens, rotate them automatically, and enforce least privilege so each identity can only do what it needs. Add monitoring and auditing so anomalous use is detected. Managed PKI and key management make this practical at scale.
Bring Your Machine Identities Under Control
Ready to inventory and secure every non-human identity? See CertSecure Manager and SSH Secure in action.