Cipher

118 BCE - 1953

Cipher

The book of science

Tom Sharp

Polybius, Julius Caesar, Giovan Battista Bellaso, Antoine and Bonaventure Rossignol, Charles Wheatstone, Frank Miller, Felix Delastelle, Fritz Nebel, Lester S. Hill, John F. Byrne cryptography

Cipher

Decoder ring

Alice, Bob, and Eve

My Polybius square is the standard 5-by-5 grid, combining letters I and J. This is a fractioning technique, since 25 characters can be represented by pairs of 5 digits.

My Caesar cipher is rot-13, rotating the alphabet ahead by 13 letters. Rotate the result ahead by another 13 gets you back to my starting point. This is called a reciprocal cipher.

The key for my Vigenère cipher is VIGENERE. Repeat the key for the length of the message and use the key letter to pick a replacement in the column for each original letter. This is called a polyalphabetic cipher.

The Great Cipher, was a homophonic substitution; the Rossignols’s nomenclators (cipher tables) used by Louis XIV of France gave numbers for syllables of the French language, which I have not tried to reproduce here.

The Playfair cipher is a literal diagram substitution, starting with, for example, the same 5-by-5 grid as the Polybius square but dropping the J. I break the message into couples, inserting the letter X to break any doubles (none in this one) and to complete the last pair, then substitute opposite corners from the grid.

My one-time pad is the opening of Abraham Lincoln’s Gettysburg Address.

My four-square uses the two keywords “example” and “keyword.”

My ADFGVX cipher starts with the Dutch code word “nachtbommenwerper.” Adding digits and filling it out to a length of 36, we get the alphabet NA1C3H 8TB2OM E5WRPD 4F6G7I 9J0KLQ SUVXYZ, which is arranged in a table using ADFGVX for both row and column headers. The initial translation substitutes the row and column headers for each letter of the message. These are arranged into another table with 12 columns with the heading PLANSOFMICED (“plans of mice and men” after eliminating duplicates). The columns are rearranged by alphabetizing the heading. Finally, the columns are read left to right.

For my Hill cipher I used the common alphabet followed by space, apostrophe, and dash, with a 4-by-4 matrix based on the key “best-Hill-cipher” (and used the dCode tool).

For my chaocipher, my cipher-text disk contains XLEMFHIWOVNYRUDQCJPASGBTKZ and my plain-text disk contains SGLBIZHJMFTRXAVKNQPDWYCUOE. Chaotic output results from modifing both alphabets for each input letter.

See also in The book of science:

Readings in wikipedia:

Other readings: