Every message can be decrypted?

I became interested in this question. Assume any message is intercepted. Is it possible to encrypt a message is not key, but replacement and word play? If there are people who can decipher these replacements? Understand that in this case, the receiver must know how and what I will replace.
July 5th 19 at 00:29
3 answers
July 5th 19 at 00:31
Yes and no.
Substitution is the key.
If You create a fairly complex replacement rules, their information capacity is comparable to the information capacity of the key.

Read about the principle Kirchhoff - it was an attempt to formalize (and to translate to a new qualitative level) that is the question that You ask.
Thank you so much! Really interesting. - Leonora.Trantow commented on July 5th 19 at 00:34
July 5th 19 at 00:33
Usually cipher based on substitutions and permutations opened simply by using frequency analysis. You only need to have enough ciphertext.
Cipher permutation is not revealed by frequency analysis - where the letters are not even changed. - Leonora.Trantow commented on July 5th 19 at 00:36
July 5th 19 at 00:35
By replacing the words stands for at times easier than what a normal encrypted by encryption algorithms.

It could be elementary for around a century ago of the mechanical ancestors of modern computers.
Yes, and before that - pure people, without computers it was decoded.
Now, with the availability of fast computers does not matter. The more posts and the longer they are, the more elementary.
How would a single, short message can't be decrypted. But you can't negotiate a new cipher each time. So you will have a few messages, long message - you'll be discovered. Easy.

When replacing the game of words if you keep the rules of speech (and they sohranyayut on long or multiple messages) is removed almost automatic.

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