# Principal Software Engineer, Windows Authentication

Source: https://startwithidentity.com/experts/steve-syfuhs/
Last updated: 2026-09-21
License: content by Start with Identity. Cite the source URL.

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## Bio

Steve Syfuhs is a principal software engineer at Microsoft working on Windows authentication, and the primary developer of Kerberos.NET, a managed-code Kerberos library now in the .NET Foundation. He previously worked on adoption of Kerberos and TLS 1.3 and on credential protection technologies including Credential Guard. He writes publicly about how Windows authentication actually works.

Profile built from public employer, project, and publication records.

## Where their work shows up

Kerberos and NTLM authenticate most of the working world and are documented mostly in specifications and vendor articles written for administrators rather than engineers. Public explanation of the internals, why a ticket looks the way it does, what Credential Guard actually protects, and what has to be true before NTLM can be turned off, is rare and load-bearing. See [Kerberoasting](https://startwithidentity.com/techniques/kerberoasting/), [Kerberos delegation abuse](https://startwithidentity.com/techniques/kerberos-delegation-abuse/), and the [ITDR guide](https://startwithidentity.com/guides/security/identity-threat-detection-response-guide/).