Capability-sealed tokens allow AI agents to use API keys without ever knowing the actual secret.
April 23, 2026
Original Paper
CapSeal: Capability-Sealed Secret Mediation for Secure Agent Execution
arXiv · 2604.16762
The Takeaway
Security in AI agents is currently a disaster because any agent with a key can be tricked into leaking it. This architecture uses a broker to swap direct access for restricted capability tokens. The agent can trigger the necessary action but the actual secret remains hidden behind a wall. It eliminates the risk of prompt injection attacks stealing sensitive credentials. Developers can finally deploy autonomous agents in production without fear of a total security breach. This moves AI safety from a request for good behavior to a hard architectural constraint.
From the abstract
Modern AI agents routinely depend on secrets such as API keys and SSH credentials, yet the dominant deployment model still exposes those secrets directly to the agent process through environment variables, local files, or forwarding sockets. This design fails against prompt injection, tool misuse, and model-controlled exfiltration because the agent can both use and reveal the same bearer credential. We present CapSeal, a capability-sealed secret mediation architecture that replaces direct secret