i think you're kind of missing the whole point of keys in cryptography. all information is binary, including keys and ciphertext. adding more characters to an alphabet doesn't do squat--it just makes it harder to read once it's decoded. if you want to encode a language L by transposing it onto another language M, it will make it more difficult for humans to read but the language itself has nothing to do with the secure transmission of that data.

so in short, i think you should read a cryptography book and then come back and see if you what you thought you knew still makes sense.