The problem of how to fetch the trust anchor for DNSSEC validation can
be solved in a number of different ways.  RFC 5011 provides a process
for updating the trust anchor, however the fundamental problem of how
to boot strap a trust anchor is a little more difficult.

Each of the solutions spans a continuum from easy for the operator but
offering weak security to hard for the operator but offering strong
security.  Some of the options we considered are:


Manual
------
If the system operator manually fetches the KSK from a well trusted
source and places it on the system he can rest assured that the trust
anchor is the most reliable.  This is also the most difficult approach
and fits least well with our goal of providing an easy to use library
for non-DNS experts.

Manual fetching can be done via a web browser, if the user ensures
that he handles the certificate for the ICANN website then it is a
respectably secure approach.


Key Fetch Tool in Source
------------------------
An application can be provided with the library that the system
operator can invoke to bootstrap the key material.  This application
would include the ICANN website and could perform the key retrieval
using a valid certificate. Although the certificate may be included in
the source tree, the certificates are typically longer lived than the
root KSK.


Key in Source
-------------
The KSK can be placed in the sources which is probably the easiest for
the system operator and is sufficiently secure provided the source
deliver process is secure.

One downside to this approach is that the source package becomes stale
following a KSK roll.  This can be partially mitigated by providing
clear diagnostic messages for the user if they attempt to validate
DNSSEC responses with outdated keys.


Automatically Fetch Key Via ICANN Website
-----------------------------------------
One of the easiest approaches is to embed the URL from which we fetch
the KSK into the sources, the library can quietly fetch the KSK if one
isn't available on the system.  This has some potential security
risks.


