It would be nice to have a code with which you can write a message on a piece of paper right from your head. And then also, from memory, without using any recorded key, read this message. Precisely to read it on the fly. Now it looks more like nonsense, because cryptanalysts have frequency analysis, brute force, even neural networks that seemingly can read almost everything that a person can encode "in the mind". But still, let's think about what approaches to such encryption can be and how much the approach can be complicated for cryptanalysts.
Honestly I must warn the reader that I passed the discipline "Coding and Information Security" with a top three and from the third time. Rather, this article is an attempt to draw attention to encryption on paper and its limitations. Nevertheless, below will be given a ready-made example of a cipher, which is enough to keep a diary and notes in a prison cell, dormitory, dysfunctional family, etc.
In fact, due to the mental abilities of a person, only a tabular cipher is suitable for us. Do not rush to close the article. We will improve it. But let's start with the basics anyway. First, we come up with 33 non-existent letters, and we put such a letter in correspondence with each real letter of the Russian alphabet. For instance:
- S, - Č, - Ť,
- W, - Ď, - Ů,
- Y, - D, - W,
- Y, - Ě, - Ý,
- U, - F, - Δ,
- I, - G, - δ,
- L, - Ň, - θ,
- Z, - Ó, - ξ,
- V, - Q, - π,
- ẞ, - Ř, - φ,
- Ť, - Š, - ψ
This is a very unfortunate set of pseudo-letters, because in writing we are not limited to any set of font characters and can invent our own, but more on that later.
" " "DSDS DθĎS DθĎF". , , . , , , . . , "", "" 4 , :
"" - " ?? ???"
"" - " ?? ???"
, , . , - , . . , . - . . , .
, : , , .
. , - . "ᛞ". " " "DSDSᛞDθĎSᛞDθĎF". , . , , "" "", , . .
, . .
. . . - , . - .
, , . 2 , - "$" "#" . "D#S$DSᛞ$DθĎ$SᛞDθ#ĎF". , , , . , , . . - ... , .
. "" - "S" "ᛟ". . ( ) : "DSDᛟᛞDθĎSᛞDθĎF". . . - , , ? , , , .
- - . , "!". - , , "", "". "!" - , , "!" . :
"ᛞθĎ!DSDᛟᛞ!FF!DθĎSᛞDθĎF"
, . . , , .
- , .
- . , . "e" , , , , - , , ? , , , , .
, . - . - - , - , .. , .
. - , : ? - , ?
, . , , . - , .
- , - .
, , . - , , . . .
, , . . . , .
, , :
How much does the enlargement of the alphabet due to dummies slow down the selection of the code?
How much does adding duplicates slow down / make frequency analysis meaningless?
How important is the transfer of the complete alphabet from paper to digital form?
What other types of computer analysis can be applied and what should be added to the table cipher?
Are there any proven cryptographically strong (within the calculated limits) encryption systems where nothing but a head is needed?