Building a Quantum Threat Model — STRIDE-Q, Data Classification, and the Indian Regulatory Frame

Manish Garg
Manish Garg Associate of (ISC)² · RingSafe
May 8, 2026
5 min read
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A quantum-era threat model extends STRIDE (Spoofing, Tampering, Repudiation, Information Disclosure, Denial of Service, Elevation of Privilege) with quantum-specific attack vectors and the time dimension that quantum computing introduces — store-now-decrypt-later. This module is the framework for documenting your organisation’s quantum risk posture: data classification by quantum-relevance horizon, threat actor capability mapping, control inventory, residual-risk scoring. Output: a quantum threat model document you can hand to auditors, the board, and Indian regulators.

Threat modelling for the quantum era is not a new framework — it’s STRIDE, attack trees, MITRE ATT&CK extended with quantum-specific considerations. The discipline is the same. The artifacts and controls change.

STRIDE-Q — quantum extensions to STRIDE

Each STRIDE category, with quantum-era considerations:

Spoofing: Quantum-broken signatures (RSA, ECDSA) become forgeable. Mitigation: PQ signatures (ML-DSA, SLH-DSA) on critical authentication. Threat actors with CRQC can impersonate any pre-quantum signed identity.

Tampering: Quantum-broken signatures on documents/transactions become forgeable. Audit trails dependent on classical signatures lose integrity. Mitigation: re-sign critical archives with PQ signatures; maintain Merkle-tree-based integrity that’s PQ-resistant.

Repudiation: Pre-quantum signatures cannot be reliably attributed post-CRQC; signers can repudiate by claiming “anyone with quantum could have forged.” Mitigation: PQ signatures + timestamping authority + log retention with PQ-signed integrity.

Information Disclosure: The dominant quantum threat. Pre-quantum encrypted data exposed when CRQC arrives. Store-now-decrypt-later is the operational risk. Mitigation: PQ KEM (ML-KEM-768) for new data; cryptographic-agility for retroactive re-encryption of high-value archives.

Denial of Service: Quantum doesn’t add new DoS vectors directly. Side note: large PQ handshake bytes increase amplification factor for some DDoS techniques; minor concern.

Elevation of Privilege: Authentication tokens (JWT, session cookies) using broken signatures become forgeable. Quantum adversary can elevate by re-signing tokens. Mitigation: PQ-signed authentication; short token lifetime; FIDO2 / hardware token for high-stakes elevation.

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