Autonomous AI agents that spawn sub-agent swarms create a safety gap: existing credential revocation mechanisms, OAuth~2.0 introspection, OCSP, and W3C Status Lists, require network connectivity to a central authority, leaving ``zombie agents'' executing privileged operations for minutes to hours after operator shutdown. We present Heartbeat-Bound Hierarchical Credentials (HBHC), a cryptographic protocol that binds credential validity to periodic parent liveness proofs. Verifiers enforce freshness using only a cached public key and local clock; no network round-trip is required. When heartbeat generation ceases, all descendant credentials become unusable within a deterministically bounded window $W_z \le W_{\max} + Δ_h + ε$, conditional on bounded clock skew and parent keys held in secure enclaves. Evaluation at the protocol layer and with real LLM-backed agent swarms (GPT-4o-mini) demonstrates a 90$\times$ reduction in the zombie window over OAuth~2.0, 0.26~ms full authentication in Rust, 18,000+ verifications per second under concurrent HTTP load, and stable per-verification latency from 10 to 10,000 agents. Real-agent experiments show 0.71\% end-to-end overhead on tool calls, zero post-revocation tool calls under prompt injection that bypasses application-layer guardrails, and cascading revocation across a 49-agent four-level hierarchy within the theoretical bound.

翻译：自主AI智能体生成子智能体群落的机制带来了安全缺口：现有的凭证撤销机制（OAuth 2.0内省、OCSP、W3C状态列表）需与中央权威机构保持网络连接，导致操作员关闭后"僵尸智能体"仍可在数分钟至数小时内执行特权操作。我们提出心跳绑定的层次化凭证（HBHC），该密码协议将凭证有效性绑定至父节点周期性存活证明。验证者仅需缓存公钥和本地时钟即可实施时效性验证，无需网络往返。当心跳生成停止时，所有衍生凭证将在确定性有界窗口$W_z \le W_{\max} + Δ_h + ε$内失效（条件为有界时钟偏差及父密钥存储于安全飞地）。协议层评估及基于真实LLM的智能体群落实验（GPT-4o-mini）表明：相较于OAuth 2.0，僵尸窗口缩减90倍；Rust实现中全认证耗时0.26毫秒；并发HTTP负载下每秒完成18,000+次验证；智能体规模从10扩展到10,000时，单次验证延迟保持稳定。真实智能体实验中，工具调用端到端开销仅0.71%，突破应用层护栏的提示注入攻击导致撤销后零次工具调用，49节点四层层次结构在理论界值内实现级联撤销。