There are dangers when allowing one TOC to refer to another, and the ability of offsets to cause self-reference, e.g. see Section 3 of http://www.ieee-security.

There are dangers when allowing one TOC to refer to another, and the ability of offsets to cause self-reference, e.g. see Section 3 of http://www.ieee-security.org/TC/SPW2014/papers/5103a198.PDF http://www.ieee-security.org/TC/SPW2014/papers/5103a198.PDF In general, it's also a good idea to keep data and metadata distinct, to avoid potential conflicts (and hence exploits). In this case having the archive metadata as a file inside the archive seems fraught with dangers. We could avoid this by e.g. having two levels of archive, e.g. the first level contains TOC files and data files (e.g. tar files); the 'payload' files are kept in the data files. That way, there's no way for payload to be interpreted as metadata, or vice versa.