• Re: Applying policy results in Bad encryption type

    From Ken Hornstein@21:1/5 to BuzzSaw Code on Tue Mar 12 16:12:27 2024
    Copy: kerberos@mit.edu (kerberos)

    We did a server replacement of our master KDC that had been on RHEL7
    for years to finally upgrade to RHEL8. We did a dump of the database
    prior to the swap, we still have the old server sitting around as
    well. Principal database is on disk in old db2 style. Kerberos
    version is 1.18 for RHEL8, RHEL7 version is 1.15.

    Everything went smooth, except any attempt to change a password results in:

    "change_password: Bad encryption type while changing password for < principal >"

    Doesn't matter if it is done over the network or with kadmin.local.

    What is the key type of the password history principal? That is in your database as kadmin/history@REALM.

    If it's something like single-DES, then that's your problem because
    the old keys are encrypted in the database with the history key and
    "Bad encryption key" is coming from the attempt to check the password
    history. If that's the case then you can change the history key to a
    modern algorithm using the command detailed here:

    https://web.mit.edu/kerberos/krb5-latest/doc/admin/database.html#updating-the-history-key

    But as detailed there that will invalidate your password history (much
    like modprinc -clearpolicy).

    In THEORY you could do some mangling on the database dump and try to
    re-encrypt the old keys with a new key; when I ran into this situation I decided that I didn't care THAT much about the old password history and
    I didn't bother doing that.

    --Ken

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