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Before encrypting text, would encoding it in a non-standard character set (such as Asahi characters) make things more secure? Maybe not to a state-actor, but to the "hacking community at large", would using non-standard character sets be more secure?

For example, Asahi character encoding is not even a part of the core Java libraries.

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  • If it would make it more secure and cryptographers knew about it, they would simply make a better cipher using that strategy. In reality, that doesn't really make much sense. Jun 14, 2018 at 2:21
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    Using another charset is essentially a substitution cipher with "blocksize" 1 (ie. the same substituion mapping for each character). This can be cracked very easily.
    – deviantfan
    Jun 14, 2018 at 5:34
  • @deviantfan that should be an answer!
    – vidarlo
    Jun 14, 2018 at 6:21
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    @deviantfan: the blocksize is not exactly 1. Conversion between charsets can change 1 byte char into 2 or 3 char bytes... Yes nitpicking ;-) Jun 14, 2018 at 11:36
  • @SergeBallesta But that doesn't change that every character is mapped by the same substituion :) That was the point. Not the byte count.
    – deviantfan
    Jun 14, 2018 at 21:29

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This style of question gets asked here often:

In addition to [some-well-known-strong-encryption-algorithm], would it be more secure to also do [some-custom-algorithm]?

The answer is nearly always the same: No, it's not more secure because it's pointless. It's similar to asking:

If I want to destroy a document and make sure no one ever reads it, I could shred it, then burn the pieces, and spread the ashes around the world. But would it be even more secure if I first crossed out the writing with a marker before shredding?

The only scenario where adding additional algorithms might help is if you are worried that your decryption key could be compromised and the custom algorithm would not be. In that contrived threat model the addition of the custom algorithm could be considered slightly more secure, but the extra energy could probably be better spent protecting the decryption key to begin with.

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  • Not in theory, but in actual practice, if storing my data as serialized Asahi characters is not a better starting point than UTF-8 English, then I just don't get it. Blending my serialized Asahi characters in with a video stream just seems like a good starting point before encryption.
    – davewp
    Jun 15, 2018 at 2:54
  • @userayu - to reiterate, it's only not "better" because it's not necessary. If you use strong encryption with a hard password, no one will ever decrypt it, so no one will ever get to see that you changed the characters or embedded it into a video. But if your decryption key is compromised, then yes, it is a little better than nothing.
    – TTT
    Jun 15, 2018 at 13:40
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No, it won't make it more secured if attacker already decrypted the data he will find the encoding type and simply decoding it it's not making it more secure just use a strong cipher AES with blocks mode of operation like CBC or CFB with 128bit block size and random 16byte key and random IV every time and your data is secured now!

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If someone is able to break the encryption of a file its not very secure to begin with. However, just assuming that we have two files, one that is encrypted, and one that is encoded then encrypted, it would be trivial to break the encoding of a file within minutes versus days / weeks for certain types of encryption.

Encoding the file before encrypting it operates essentially the same as a substitution cipher, read here But the premise is that each individual character would be substituted or swapped for another value. History tells us that the first substitution cipher was written by Leon Battista Alberti in 1467, and was built on to create the Caesar Cipher. The link above gives a good deal more info on this sort of cipher.

So technically it might slow someone down since they would have to find out what the encoding is, and then substitute the values in, but if they made the effort to break the encryption you can be sure they'll be able to decode the file afterwards!

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