SOLIDPOD: add permission record verification to ensure veracity of past permission

[jesscmoore]

Description

The permission log file is appendable by any authenticated user. This forms only a weak protection against unauthorised editing.

This issue is to consider some form of cryptographic verification or other, that checks a permission is correct before it is loaded in the app. When permissions are granted/revoked/changed, a permission record is appended to the logs of the owner, granter and recipient. As the owner of a resource is constant, so their permission log (filtered for the resource) contains all permission changes to that resource. Whereas the permission records of a resource in the granter and recipient will be only a subset of the owner's set. A permission record will not necessarily match the ACL, as ACL only shows the current permissions. Verification of a permission record could be made by checking for a match of that permission record (or some representation of it) against the owner's permission record.

Why

So that as a owner or granter I want to know that records in the permissions history for a resource are true and accurate.

Closing Criteria

Checklist for closing the issue:

• No errors from make prep
• All tests pass make qtest
• Verification to ensure the veracity of past permission records.

Alternatives

Interested in alternate options to achieve this feature.