As Quantum Computing Threats Loom, Microsoft Updates Its Core Crypto Library

An anonymous reader quotes a report from Ars Technica: Microsoft has updated a key cryptographic library with two new encryption algorithms designed to withstand attacks from quantum computers. The updates were made last week to SymCrypt, a core cryptographic code library for handing cryptographic functions in Windows and Linux. The library, started in 2006, provides operations and algorithms developers can use to safely implement secure encryption, decryption, signing, verification, hashing, and key exchange in the apps they create. The library supports federal certification requirements for cryptographic modules used in some governmental environments. Despite the name, SymCrypt supports both symmetric and asymmetric algorithms. It's the main cryptographic library Microsoft uses in products and services including Azure, Microsoft 365, all supported versions of Windows, Azure Stack HCI, and Azure Linux. The library provides cryptographic security used in email security, cloud storage, web browsing, remote access, and device management. Microsoft documented the update in a post on Monday. The updates are the first steps in implementing a massive overhaul of encryption protocols that incorporate a new set of algorithms that aren't vulnerable to attacks from quantum computers.

The first new algorithm Microsoft added to SymCrypt is called ML-KEM. Previously known as CRYSTALS-Kyber, ML-KEM is one of three post-quantum standards formalized last month by the National Institute of Standards and Technology (NIST). The KEM in the new name is short for key encapsulation. KEMs can be used by two parties to negotiate a shared secret over a public channel. Shared secrets generated by a KEM can then be used with symmetric-key cryptographic operations, which aren't vulnerable to Shor's algorithm when the keys are of a sufficient size. The other algorithm added to SymCrypt is the NIST-recommended XMSS. Short for eXtended Merkle Signature Scheme, it's based on 'stateful hash-based signature schemes.' These algorithms are useful in very specific contexts such as firmware signing, but are not suitable for more general uses. Monday's post said Microsoft will add additional post-quantum algorithms to SymCrypt in the coming months. They are ML-DSA, a lattice-based digital signature scheme, previously called Dilithium, and SLH-DSA, a stateless hash-based signature scheme previously called SPHINCS+. Both became NIST standards last month and are formally referred to as FIPS 204 and FIPS 205. In Monday's post, Microsoft Principal Product Manager Lead Aabha Thipsay wrote: 'PQC algorithms offer a promising solution for the future of cryptography, but they also come with some trade-offs. For example, these typically require larger key sizes, longer computation times, and more bandwidth than classical algorithms. Therefore, implementing PQC in real-world applications requires careful optimization and integration with existing systems and standards.'

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