Threat-Reactive Encryption: Real-Time ML-Driven Key Rotation for Adaptive Cryptographic Defense
: Static key rotation policies are structurally mismatched to machine-paced adversaries that can exfiltrate session keys within a single cryptoperiod. This paper presents Threat-Reactive Encryption (TRE), a four-layer framework that couples a real-time ML threat scorer to a PKCS#11-compatible key management pipeline, closing the gap between threat detection and cryptographic response. A 47-feature telemetry vector from network flows, TLS handshake metadata, syscall traces, and hardware performance counters (HPCs) is scored every 500ms by an XGBoost+Isolation Forest ensemble inside a hardware-attested Trusted Execution Environment (TEE). Rotation fires atomically when the unified threat score exceeds a Bayesian adaptive threshold, installing new key material via TLS1.3 post-handshake authentication without session interruption. On a 168-hour, 10Gbps testbed with 500 concurrent TLS1.3 sessions and 12 injected CALDERA attack cam-paigns, TRE achieves macro-AUPRC=0.952, median rotation latency=57ms (P99=163ms), and steady-state FPR ≤ 2 . 0% with zero session resets. Post-compromise key exposure is reduced 625 × vs. the 24-hour static policy and 26 × vs. the 1-hour static policy. Adversarial analysis shows full evasion requires the attacker to operate at ≈ 7% of unconstrained attack throughput. The approach is PKCS#11-compatible and provides a direct extension path to post-quantum algorithm substitution via CRYSTALS-Kyber (NIST FIPS203).