Tag Archives: SPIFFE

Rethinking Authentication: “Something You Have,” “Something You Know,” and “Something You Are” for Workloads and Machines

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Passwords have existed for millennia, and their weaknesses have persisted just as long. Their simplicity led to widespread adoption, but as their use expanded, so did the frequency of their abuse. To address this, we implemented stricter password policies—longer lengths, special characters, regular changes—much like hiding vulnerable software behind firewalls. When these efforts fell short, we evolved to multi-factor authentication (MFA), introducing the principles of “Something You Have,” “Something You Know,” and “Something You Are.”

MFA brought its own challenges—deployment complexity and user friction. Password managers helped bridge some gaps by generating and storing random passwords for us. While each of these steps enhanced security, none addressed the core problem: passwords and shared secrets are fundamentally flawed authenticators. This realization spurred efforts like WebAuthn, FIDO, and Passkeys, which replaced passwords with cryptographic keys and secure protocols, eliminating shared secrets entirely.

However, while user authentication evolved, workload and machine authentication lagged behind. Instead of passwords, workloads relied on API keys—essentially shared passwords—managed through “password managers” rebranded as secret vaults. These shared secrets are just as fragile and inadequate for today’s complex, scaled environments as passwords were for users.

The path forward is clear: workloads and machines need their own authentication revolution. We must replace shared secrets with cryptographic keys and implement MFA for workloads. But what does machine-focused MFA look like? Let’s explore how the three fundamental authentication factors apply to workloads and machines.

Applying Authentication Factors to Workloads and Machines

1. Something the Workload Has

This encompasses physical or cryptographic elements unique to the workload:

  • Hardware Roots of Trust: Security processors like TPM, Microsoft Pluton, Google Titan, and Apple’s Secure Enclave provide tamper-resistant foundations for device identity and posture assessment.
  • Cryptographic Keys: Private keys secured within hardware security processors serve as a robust “something you have,” enabling strong authentication.
  • Credentials: Like OIDC tokens and X.509 certificates, uniquely identify machines and workloads within trusted environments.

These mechanisms form the backbone of secure workload authentication, much like physical security tokens do for human users.

2. Something the Workload Knows

This parallels knowledge-based authentication but focuses on workload-specific secrets:

  • Shared Secrets: Shared API keys, symmetric keys, and asymmetric credentials that are used for authentication.
  • Configuration Data: Runtime-specific information like environment configuration.

Although often necessary for a service’s functionality, these weak attributes are highly susceptible to exposure, reuse, and theft. Implementing credentialing systems like SPIFFE can significantly mitigate these risks by replacing shared secrets with cryptographically secure, short-lived credentials uniquely tailored to each workload.

3. Something the Workload Is

This represents inherent characteristics of the workload, similar to human biometrics:

  • Trusted Execution Environments (TEEs): Secure enclaves like Intel SGX or AWS Nitro verify and attest to the integrity of the workload’s execution environment.
  • Immutable Code or Container Hashes: Binary or container image hashes verify workload integrity.
  • Runtime Attestation: Environmental and configuration validation ensures compliance with security policy.
  • POSIX Process Names and Metadata: Process information and runtime metadata provide operational context.

By combining these attributes, workloads can demonstrate their role and environment to enable more contextual identification and authorization.

The Future of Workload Identity

Authentication factors vary in strength—cryptographic keys and runtime attestations can provide strong confidence in what you are talking to while process names and secrets offer weaker assurance. Combining these elements creates a more comprehensive picture of workload authenticity. Standards like SPIFFE leverage this combination, creating strong workload identities by incorporating hardware roots of trust, runtime attestations, and other security properties. Over time, these attestations can be enriched with supply chain provenance, vulnerability assessments, and other compliance data.

As we look further ahead to agentic workloads and AI systems, we will need to develop protocols and policies that enable us to consider both workload identity and the entities they represent. For example, an AI model handling financial transactions needs both verified workload identity and specific policies for each user it serves so that the agent does not become a way to escalate privileges and access data that would otherwise have been unreachable.

This evolving, layered approach ensures that workload authentication scales with increasingly complex machine ecosystems while maintaining security and accountability. By unifying identity, actions, and policies, we prepare for a future of autonomous yet accountable workloads.