DDSSEC12 — How are 'subject_name' fields compared?

In 9.4.1.3.2 Grant Section, the spec states:

"A permissions [sic, should be grant] Section with a subject name that does not match the subject name given in the corresponding Authorization certificate shall be ignored."

It is not clear what algorithm should be applied to determine if two subject_names "match"; and this has interoperability implications.

A 'simple' approach would be a simple string comparison.

A 'complex' approach would be to do the following:

1) parse each subject_name as a series of name=value pairs,
2) check that all name's exist in each subject_name
3) check that for each name, the corresponding 'value' matches, using regex (for example fnmatch(), or similar) processing.

The more complex approach might be beneficial, because it could support using a 'wildcard' Common Name. For example, in the permissions file, use a Subject Name like this:

      <subject_name>/C=US/ST=CO/O=Twin Oaks Computing/CN=*.twinoakscomputing.com/emailAddress=support@twinoakscomputing.com</subject_name>

Then, the Identity Cert's could be constructed with a more specific Subject Name, like "CN=participant1.twinoakscomputing.com", and it would match.