HashiCorp Vault vs Trussed: AI Agent Secrets and Authorization
HashiCorp Vault and Trussed address different layers of AI agent security. Vault manages the lifecycle of secrets and credentials: issuing, rotating, and revoking access based on identity-scoped policies. Trussed provides runtime governance for AI agents, evaluating individual tool calls, enforcing least-privilege permissions per action, and logging decision context. Most enterprise AI agent stacks need both: Vault for credential management and a runtime authorization layer for per-action policy enforcement and auditability.
Two different security boundaries
Vault and Trussed sit at distinct points in the agent security stack. Understanding the boundary each one governs makes it clear why the two are complementary rather than substitutes.
Credential lifecycle
Issuance, rotation, and revocation of secrets an agent uses to reach a system.
Action authorization
Evaluation of what the agent does with that credential, call by call.
Identity binding
Mapping an authenticated agent identity to both a credential and a permission set.
Audit trail
Records of what was accessed versus records of what was requested, decided, and why.
Where MCP security fits
As agents call tools through the Model Context Protocol, credential possession and action legitimacy become separate questions. A valid credential does not confirm that a given tool call, with its specific parameters, was the right action to take.
Combined integration pattern
Enterprises running AI agents typically need both layers rather than choosing one over the other: Vault for credential lifecycle, and a runtime authorization layer for per-action policy enforcement.
Evaluation criteria for security engineers
Questions worth asking when comparing a secrets manager against a runtime authorization layer, or when deciding whether both are required.
- Does the layer evaluate individual tool calls and actions, or only initial authentication and credential issuance?
- Does it log agent decision context, such as intent, tool, and parameters, rather than only credential access events?
- Which MCP specification version, including authorization capabilities, does it support?
- Can the secrets manager and the runtime authorization layer reference the same agent identity for consistent policy decisions?
- What is the incident-response path if an agent takes an unauthorized action using a validly issued credential?
Common questions
Does Trussed replace HashiCorp Vault?
No. Vault manages secret and credential lifecycle. Trussed evaluates and governs the actions an agent takes once it has access, including tool calls made through MCP. They operate at different layers and are typically deployed together.
Is Vault alone sufficient for securing AI agents?
Vault secures credential issuance and rotation, which reduces standing credential exposure. It does not evaluate the content or sequence of actions an agent takes after receiving a credential, which is a separate risk category requiring runtime policy enforcement.
What does least privilege mean for an AI agent, specifically?
Beyond scoping a credential to a system, least privilege for an agent means restricting which tools, actions, and parameters it can invoke for a given task, and enforcing that scope at the moment of each tool call rather than only at authentication.
Secrets management and agent authorization are not the same control
If your AI agents already authenticate through Vault, the next question is whether individual tool calls are evaluated against policy before they execute.
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