content: To invent a new secure algorithm requires a heinous amount of knowledge. Implementing an existing one that is generally accepted by the people with heinous amounts of knowledge less so but you can still fuck up the implementation that opens up possibilities to defeat it without having to overcome the algorithm. I don't know what specific age is required but the algorithms and reference implementations in code are already out there so it cannot be physically stopped only made illegal when detected. The field of steganography takes things a step further by making it difficult to detect whether an encrypted message is even present.