authpolicy: Set strong Kerberos encryption types in smb.conf

Samba internally creates a krb5.conf file that by default contains
encryption types we consider weak. This CL sets a parameter in
smb.conf that forces Samba to use strong entryption types only.

CQ-DEPEND=CL:430692

BUG=chromium:662390
TEST=Verified that the internally created entryption types are strong.

Change-Id: I09035188f333559e38508cebd3bdaa48000ae7f6
Reviewed-on: https://chromium-review.googlesource.com/430671
Commit-Ready: Lutz Justen <ljusten@chromium.org>
Tested-by: Lutz Justen <ljusten@chromium.org>
Reviewed-by: Thiemo Nagel <tnagel@chromium.org>
1 file changed