Saying that it was easy for anyone to decipher is easy with the encipher is like saying Enigma was easy to break once you had both machines.
Using the example of language is bullshit as well since I don't need anything third party to decipher your Mexican since I could naturally speak it. But there is no way I could decipher what you're saying without the key.
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also your claim is bs since you give no role and green txt isn't enough.