The security I'm talking about is DRM protection.
(See here: Implementing the IHO Security Scheme
What I want to do is produce a viewer which can be freely distributed to enable the viewing of S.63 protected data.
I don't need a full S.63 implementation though. The keys are distributed in a proprietary 'DRM' encrypted format, and will be handled by the viewer with no user interaction.
In this way I can remove the S.63 protection, but I don't want to expose the chart to possible copying while unprotected, so the decryption and decompression are handled in memory.
Of course this is weakened if I then need to write the unprotected chart to HDD so that it can be loaded, so I'd rather load it from memory if possible.
However, if the SENC is also not secure can just be copied onto another system and re-used, this would be an unacceptable vulnerability.
It's possible that this is too much additional coding to add to this app, but I've been working on this for a while before someone sent me a link here, so any suggestions would be greatly appreciated!