If, from the root of the Android SDK, I issue this command:
tools/emulator -help-sim-access-rules-file
I get the following message:
Textproto configuration file for overriding SIM access rules (see sim_access_rules.proto for structure)...
Where can I find this sim_access_rules.proto file? Or if sim_access_rules.proto is not publicly accessible, what is the proper format for the sim access rules configuration file?
There is no sim access rules file in the Android source repo, or at https://android.googlesource.com/. The emulator command line docs make no mention of the sim-access-rules-file argument. I think you can assume this is an option meant for internal use only.
Secure Element access control is used in addition to existing protection mechanisms (such as permissions or security OS policy limiting access to sensitive APIs). The access control is designed to prevent unauthorized access to resources in the Secure Elements and typically to prevent denial of services attacks (PIN blocking, selection of non multi-selectable applets, etc.).
Find details of SIM access rules here along with data structure: https://source.android.com/devices/tech/config/uicc
Find detailed specifications here: https://globalplatform.org/specs-library/secure-element-access-control-v1-1/#