LLM API Key Management: Vaults, Rotation, and Least Privilege

An exposed LLM API key is a credit card with no spending limit and no name on it. Credential sprawl is one of the most common AI security failures — keys pasted into shared chats, committed to repos, and reused across every tool and teammate.

LLM API key management is the discipline that prevents this: vaults, per-key scoping, rotation, and least privilege. This guide covers the policy and the mechanics. LayerFlow's key vault implements it for BYOK users; the docs show the setup and pricing the plans.

Principle 1: Keys live in vaults, not files

A key belongs in an encrypted store with access control: a secrets manager, a tool's key vault, or a password manager — never in source code, .env files committed to git, or chat messages. The test is simple: if a teammate joins the repo and the key is readable, the key is compromised.

Principle 2: One key per purpose

Create a separate key per tool, per environment (dev, staging, prod), and per client. A leaked CI key then revokes without breaking your editor integration. Scoped keys also make provider dashboards useful: the key burning the most tokens is identifiable by name.

Principle 3: Rotation on a schedule

Rotate keys quarterly, immediately after a suspected leak, and when anyone with access leaves. Automation beats calendars: most providers allow multiple active keys, so rotate with an overlap window and zero downtime. Full process in the rotation guide.

Principle 4: Least privilege

A key should do one job with the minimum permission: read-only where possible, per-model if the provider supports it, with a spend cap that matches its purpose. A key with org-level permissions and no cap is an incident waiting for a trigger.

The written policy

• Keys never appear in code, chats, or docs.
• One key per tool and environment, named consistently.
• Rotation quarterly and on any personnel change.
• Spend caps on every key.
• Revocation within one hour of a suspected leak.

Common mistakes

• Sharing one team key — attribution dies and leaks are catastrophic.
• Committing .env files to repositories.
• Never rotating, so every former teammate still holds live keys.
• No per-key caps — one leak becomes a five-figure bill.
• Storing keys in AI chats where they train models' context.

Internal next steps

Continue with Secure AI Key Management and Managing Multiple LLM API Keys. For teams, read Team API Keys Without the Security Nightmare.

Put your keys in a real vault: sign in to LayerFlow and connect keys with per-purpose scoping, or review pricing first.

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