The identity.xml file contains the SNF license id and authentication string for the SNF node.
<!-- Change 'licenseid' and 'authenticationxx' to match your license info -->
<snf><identity licenseid='licensid' authentication='authenticationxx'/></snf>
Although it is possible to include the license id and authentication string in the main configuration file, having it in a separate identity.xml file makes it easier to share one configuration among many SNF nodes - each with their own identity. This separation also makes it safer to post questions and share parts of configuration files since they don't contain sensitive authentication data.
Please email email@example.com with any questions.