A Cryptography Engineer’s Perspective on Quantum Computing Timelines

NIST stated:

CSRC | NIST – 3 Jan 17

Post-Quantum Cryptography | CSRC | CSRC

Short URL: https://www.nist.gov/pqcrypto For a plain-language introduction to post-quantum cryptography, see What Is Post-Quantum Cryptography? PQC Standards | Migration to PQC | Ongoing PQC Standardization Process NIST’s Post-Quantum...

Taking these mitigating factors into account, it is quite likely that Grover’s algorithm will provide little or no advantage in attacking AES, and AES 128 will remain secure for decades to come. Furthermore, even if quantum computers turn out to be much less expensive than anticipated, the known difficulty of parallelizing Grover’s algorithm suggests that both AES 192 and AES 256 will still be safe for a very long time. This of course assumes that no new cryptographic weaknesses, either with respect to classical or quantum cryptanalysis, are found in AES.

So, the security of AES-128 will depend on when “much less expensive” quantum computers become available.

In February 2025, Microsoft introduced the Majorana 1 chip prototype.

Microsoft Azure Quantum Blog – 19 Feb 25

Microsoft unveils Majorana 1, the world’s first quantum processor powered by...

Majorana 1 from Microsoft is the world’s first Quantum Processing Unit (QPU) built with a topoconductor. Discover more.

Est. reading time: 7 min read

Although it is still just a prototype, if Microsoft succeeds and their claims turn out to be true, then AES-128 could be in danger in maybe 5–10 years rather than decades.

PCMAG – 19 Feb 25

Microsoft: New Chip Means Quantum Computing Is 'Years, Not Decades' Away

The breakthrough with Majorana 1 comes after a nearly 20-year quest to harness a new state of matter, which Microsoft says it has now done with its 'topological superconductors.'

So yes, “severe danger” is exaggerated, but it is still in real potential danger. That’s why NIST recommended (and many experts continue to recommend) using AES-192 or AES-256 for long-term protection.