Stash file /etc/krb5kdc/stash uses DEPRECATED enctype des3-cbc-sha1

Bug #1969676 reported by Andreas Hasenack
This bug report is a duplicate of:  Bug #1981697: KDC: weak crypto in default settings. Edit Remove
8
This bug affects 1 person
Affects Status Importance Assigned to Milestone
krb5 (Debian)
Fix Released
Unknown
krb5 (Ubuntu)
Triaged
Medium
Unassigned

Bug Description

When provisioning a new realm, this warning is logged in /var/log/syslog:

==> /var/log/syslog <==
Apr 20 20:43:16 kdc systemd[1]: Starting Kerberos 5 Key Distribution Center...
Apr 20 20:43:16 kdc krb5kdc[3136]: Stash file /etc/krb5kdc/stash uses DEPRECATED enctype des3-cbc-sha1!

This comes from "master_key_type" in the default kdc.conf shipped in krb5-kdc:

$ cat /usr/share/krb5-kdc/kdc.conf.template
[kdcdefaults]
    kdc_ports = 750,88

[realms]
    @MYREALM = {
        database_name = /var/lib/krb5kdc/principal
        admin_keytab = FILE:/etc/krb5kdc/kadm5.keytab
        acl_file = /etc/krb5kdc/kadm5.acl
        key_stash_file = /etc/krb5kdc/stash
        kdc_ports = 750,88
        max_life = 10h 0m 0s
        max_renewable_life = 7d 0h 0m 0s
        master_key_type = des3-hmac-sha1
        #supported_enctypes = aes256-cts:normal aes128-cts:normal
        default_principal_flags = +preauth
    }

The kdc.conf manpage says that the current default is "aes256-cts-hmac-sha1-96". The sample
kdc.conf in the documentation at https://web.mit.edu/kerberos/krb5-latest/doc/admin/install_kdc.html#kdc-conf suggests just "master_key_type = aes256-cts".

Changing encryption defaults should be done carefully, even when suggested by upstream. I filed bugs.debian.org/1009927 in debian as well.

Changed in krb5 (Ubuntu):
status: New → Triaged
importance: Undecided → Medium
Changed in krb5 (Debian):
status: Unknown → New
Changed in krb5 (Debian):
status: New → Fix Released
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