If you are a developer working for the government and in charge of this, please do not make this mistake. If you are the President of the United States and need to send a message like this, please make it completely unambiguous. Maybe repeat it several times and provide a justification.

I'm fairly confident that the US government, given that it runs the NSA, has access to a textbook or two on applied cryptography and cryptanalysis and does not need to source input on their cryptographic designs from HN :)