Tool to decrypt / encode with 3 squares cipher. Three-square encryption uses three 5 by 5 grids to combine to extract letters with a bit randomness.
Three Squares Cipher - dCode
Tag(s) : Polygrammic Cipher
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3-square encryption is done with three grids (possibly generated from a keyword)
Example: Encrypt MESSAGE with the keys ONE, TWO, THREE' corresponding to the grids
Split the plain message into bigrams (pairs of two letters L1 and L2). Find L1 in grid 1 and L2 in grid 2. Then note the intersection in grid 3 of the line of L1 in grid 1 with the column of L2 in the grid 2.
Example: For the bigram ME, M is in position (line 3, column 5) in grid 1, and E is in position (line 2, column 3) in the grid 2. The intersection in grid 3 is the letter K (line 3, column 3).
Each bigram of the plain text is associated with 3 new letters: a letter taken randomly in the same column as the letter in the grid 1, the letter intersection of the grid 3 and a letter taken randomly in the same line as the letter of the grid 2. These 3 letters (a trigram) represent the coded text for the bigram.
Decryption by three squares is done with three grids.
Example: Decrypt UDBJDC with the keys ONE, TWO, THREE' corresponding to the grids
Example: The first trigram is UDB, U is in position (line 5, column 1) in grid 1, D is in position (line 2, column 3) in grid 3, and B is in position (line 1, column 5) in grid 2.
Find the 2 plain letters:
Plain letter 1: intersection of the line of the letter L2 in the grid 3 with the column of the letter L1 in the grid 1
Plain letter 2 : intersection of the letter L2 column in grid 3 with the line of the letter L3 in grid 2.
Example: The first plain letter is C, intersection of line 2 of D in grid 3 with column 1 of U in grid 1.
The second plain letter is' O ', intersection of column' 3 of D 'in grid' 3 'with line' 1 of B 'in grid' 2 '.
Finally the complete plain message is' CODE'.
There are several ways to encrypt and note the letters:
The first letter of the bigram is searched in grid 1 and the second letter in grid 2 (encryption 1-2) but it is possible to invert (encryption 2-1)
The trigram is then generally noted as:
- a letter taken randomly in the same column as the letter in the grid 1
- the letter of the grid 3
- a letter taken randomly in the same line as the letter of the grid 2
This encryption is said (1-3-2). It is of course possible to encrypt with a different order.