Charles, That is actually a KDC implementation detail, but the MIT KDC generates a key from the password at password change time (using a derivation function specific to each enctype and saves a key for each enctype, togteher with a key version number). As a data point this is the same data you obtain in a keytab.
A KDC cannot really store *a* hash, because clients do not send passwords for authentication. HTH, Simo. On Tue, 2026-06-23 at 20:16 +0000, Charles Hedrick via Kerberos wrote: > does the encrypt affect the way user passwords are hashed in the KDC. (I > assume password hashses are stored, not passwords in the clear?) > > > ________________________________________ > From: Greg Hudson <[email protected]> > Sent: Tuesday, June 23, 2026 4:12 PM > To: Charles Hedrick; [email protected] > Subject: Re: why is aes sha1 the default encryption type > > On 6/23/26 08:43, Charles Hedrick via Kerberos wrote: > > When there's a perfectly good aes sha2 type? > > 1. It is highly interoperable. Every Kerberos implementation of > significance implements aes-sha1, going back many years. Microsoft > either hasn't implemented aes-sha2 or only implemented it in 2025 (I > can't easily tell which), so the clock has at best barely started on > that kind of reach for aes-sha2. > > 2. The known flaws in SHA-1 do not affect its use as a MAC. > > 3. Kerberos enctype negotation isn't perfect. It works well enough for > client interoperability, but when provisioning keytabs for servers you > have to select an enctype that the server software supports. There is > also this edge case if it hasn't been fixed on the Microsoft side: > https://krbdev.mit.edu/rt/Ticket/Display.html?id=9089 > > I get that using SHA-1 in any capacity can run afoul of regulatory > systems, which aren't always nuanced enough to recognize that it is > still believed to be secure as a MAC. But changing the default doesn't > necessarily help with compliance; as long as the system can negotiate > down to aes-sha1 then it still has SHA-1 in its attack surface. > > > ________________________________________________ > Kerberos mailing list [email protected] > https://mailman.mit.edu/mailman/listinfo/kerberos -- Simo Sorce Distinguished Engineer RHEL Crypto Team Red Hat, Inc ________________________________________________ Kerberos mailing list [email protected] https://mailman.mit.edu/mailman/listinfo/kerberos
