Policy Considerations Phill Hallam Baker

We have a choice

Choice 1

If it works don’t break it

Choice 2

Do the job right

An Architecture

A master plan

If we have to change Layered Architecture Reusable Policy Statements Reusable discovery strategy

You can’t have security without security policy

SSL Should I use security?

S/MIME, PGP No policy layer Authentication has limited use

STARTTLS The best encryption we have Should be used 100% Vulnerable to a downgrade attack

We can fix discovery Without changing the DNS infrastructure Or waiting for it to change

Three step discovery 1) policy = lookup (TXT, "_dkim.alice.example.com") IF policy <> NULL THEN RETURN policy 2) pointer = lookup (PTR, “alice.example.com") IF pointer == NULL THEN RETURN NULL 3) policy = lookup (TXT, "_dkim." + pointer) return policy To specify a wildcard use: *.example.com PTR _default.example.com

Choice 1 is best

Don’t boil the ocean

Unless we have to

Don’t end up with