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Sesame’s core security guarantee is simple: your AI agent never sees the credential. Instead of handing secrets to agents and hoping they stay contained, Sesame acts as a broker that intercepts every outbound API call, resolves the required credential from its vault, injects it at the network level, and forwards only the response body back to the agent — the secret itself never touches agent memory, logs, or context windows.

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The Three Leak Surfaces Sesame Eliminates

Most credential leaks in AI systems happen at one of three well-known surfaces. Sesame is designed to close all three.
Common credential leak surfaces in AI agent systems:
  1. Environment variables — Secrets passed via ENV are trivially exposed through log output, prompt injection attacks, or a simple printenv call inside the agent’s execution environment.
  2. Tool arguments — Credentials passed as tool call arguments live in the agent’s context window. A sufficiently crafted user prompt can cause the model to echo them back verbatim.
  3. MCP servers with baked-in credentials — An agent that can read its own configuration file can read any credentials stored there, regardless of file permissions.
Sesame eliminates all three surfaces by design. Your agent passes only a hostname reference to the sesame request command — it never receives, stores, or transmits the credential itself. The broker resolves the right secret from AWS Secrets Manager, injects it as an Authorization header, and returns only the HTTP response body. At no point does the credential value travel through the agent process.

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Cryptographic Device Identity

Every Sesame agent is tied to a cryptographic identity established at login — not a shared password or static API key, but an asymmetric keypair.
  • Ed25519 keypair generated on-device — A fresh Ed25519 keypair is generated locally when the agent authenticates for the first time.
  • Private key never transmitted — The private key is stored only on the device and is never sent to the broker under any circumstances.
  • Challenge-response authentication — To prove its identity, the device goes through a challenge-response flow: the broker sends a random nonce, the device signs it with the private key, and the broker verifies the signature against the stored public key.
  • Scoped access JWT issued — On successful verification, the broker issues an EdDSA JWT scoped to that specific device. This token accompanies every subsequent sesame request call.
Because the JWT is derived from a keypair the broker never has full possession of, stolen tokens from one device cannot be replayed from another.

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Per-Hostname Policies

Sesame enforces access control at the hostname level. For every agent, you define which HTTP methods and URL path patterns are permitted for each target API. Requests that match a policy are handled automatically. Requests that fall outside any defined policy are held for human approval before any credential is injected. This means a compromised or misbehaving agent cannot silently pivot to a new API endpoint — Sesame will block the request and notify you before anything is sent.

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The Four Pillars of Sesame’s Security Model

Cryptographic Identity

Every agent authenticates via Ed25519 challenge-response. The private key never leaves the device, and the broker issues a scoped EdDSA JWT that proves identity on every request.

Hostname Policies

Per-agent, per-hostname rules define exactly which HTTP methods and path patterns are permitted. Anything outside the policy is blocked until you explicitly approve it.

JIT Approval

The first time an agent targets a new hostname, Sesame blocks the request and notifies you in real time. You approve or deny before any credential is ever injected.

Instant Revocation

Deactivate an agent, remove a single approval, or delete the IAM role entirely. Because Sesame verifies the JWT on every request, revocation takes effect immediately — no key rotation required.
Want to understand exactly what happens when an agent hits a new hostname for the first time? See Human Approval Flow for a step-by-step walkthrough of the just-in-time approval process.