Microsoft Urges Threat Modeling to Prepare for Post-Quantum Cryptography Migration

Microsoft is urging organizations to use threat modeling to discover cryptographic dependencies that could become vulnerable as quantum computing advances. The company emphasized that identifying these risks early can help businesses prepare for the shift to quantum-resistant security and avoid costly disruptions during the transition.

One of the biggest challenges in transitioning to post-quantum cryptography (PQC) is that many organizations lack a complete understanding of how cryptography is used across their systems. Cryptographic functions may be embedded in operating systems, third-party software, cloud services, hardware, or custom applications, which makes them difficult to identify and assess. Microsoft notes that replacing vulnerable algorithms with quantum-resistant alternatives requires organizations to discover these dependencies, evaluate their risks, and determine how to migrate them without disrupting existing operations.

According to Microsoft, threat modeling can help close this gap by enabling organizations to examine assets, data flows, trust boundaries, and security controls to discover cryptographic dependencies that may otherwise go undocumented. It provides a structured way to analyze system designs, identify potential security threats, and determine the safeguards needed to reduce those risks.

What are the key steps for PQC Migration?

To support post-quantum cryptography planning, security teams need to examine their cryptographic environment in detail. This includes identifying the algorithms, protocols, key sizes, and security configurations in use, understanding who is responsible for managing cryptographic components, assessing whether existing implementations can be upgraded without major disruption, and reviewing how cryptographic keys are generated, stored, rotated, and retired.

Organizations should also evaluate whether sensitive data could be exposed to future “harvest now, decrypt later” attacks, where encrypted information collected today may be decrypted once powerful quantum computers become available.

TLS 1.3 becomes a foundation for Post-Quantum security

Microsoft urges organizations to assess whether existing cryptographic mechanisms are quantum-resistant and provides a roadmap for upgrading vulnerable technologies. The company has detailed a couple of migration steps, including moving from 1.2 to TLS 1.3 and adopting hybrid TLS 1.3 key exchange mechanisms that combine traditional cryptography with ML-KEM.

It’s also recommended to replace RSA and elliptic curve-based key establishment methods with ML-KEM, and transition to stronger security standards (such as AES-256, SHA-384), and post-quantum digital signature algorithms (like ML-DSA and SLH-DSA). These changes can help organizations strengthen their defenses and prepare for a quantum-secure future.

Microsoft emphasized that TLS 1.3 is a basic requirement for PQC adoption. Older versions of TLS don’t support the hybrid post-quantum key establishment mechanism required for quantum-resilient connections.

Microsoft notes that the cloud provider generally manages the implementation of PQC-capable infrastructure under the shared responsibility model for organizations using Azure PaaS services. However, customers would be responsible for understanding their dependencies and designing applications with crypto-agility, which allows cryptographic changes with minimal disruption in the future.

Microsoft plans to transition critical products and services to post-quantum cryptography by 2029 due to growing quantum computing risks. The company says organizations should first build a detailed inventory of cryptographic algorithms, protocols, assets, and dependencies to identify vulnerabilities and plan migrations.