Actually have another look at that before you break the law on this yourself.
As far as I can see that article says that reverse engineering is legal in the case that: (1) the EULA doesn't mention it (I've no idea what Whatsapp EULA says - do you?). (2) it is done for the purpose of interoperability. What is being proposed by the GP is in fact not interoperability but security testing.
As I said before I think that the laws on this are stupid. But why worry about this when there is a great FOSS program in the same space?
As far as I can see that article says that reverse engineering is legal in the case that: (1) the EULA doesn't mention it (I've no idea what Whatsapp EULA says - do you?). (2) it is done for the purpose of interoperability. What is being proposed by the GP is in fact not interoperability but security testing.
As I said before I think that the laws on this are stupid. But why worry about this when there is a great FOSS program in the same space?