[image of digits]

Collections in Cryptology - Paper Alphabets
Key mechanisms in computation...

Alphabetic substitution ciphers exclusively on paper with no mechanical contrivances.
The Ché Guevara Cipher
A double enciphered system (a straddling checkerboard and Vernam-type one-time key) cipher found with Ché Guevara when he was captured.
It was used in this message fragment addressed to Fidel Castro dated May 18, 1967.
Source: David Kahn, KAHN ON CODES, MacMillan, New York (1983).


Ché's "straddling checkerboard" worksheet in which the numeric keys (highlighted in yellow and pink)
as well as the keyword "estadoy," followed by the remainder of the alphabet, filled out the table..
Letters are indexed by their two numeric coordinates, first by row (pink) and then by column (yellow).
Blank (white) cells are used as spaces. Gray cells are never used.
"73" marks the following code as a number. "77" marks the following code as a letter.
Numbers are repeated three times for the conversion..

Compare this with Ana Montes' "straddling checkboard cipher."



Plaintext is first converted to numbers using the "straddling checkerboard".
The conversion is then added, column by column (modulo 10), to the key to give the ciphertext.
Finally, the ciphertext is grouped into "words" of five digits in length (not shown).
A Numerically Indexed Alphabetic Table
It might be changed on a periodic schedule or used only once.
For our purposes, let's index the letters with the line number first, then the column.
A Candidate for a Pseudo-Random Key, Steganographically Hidden in Plain Sight
The sender and receiver may secretly agree to use some widely published material as a daily key.
It might be a newspaper article, letters or numbers read down a column on a page in a telephone book, or the low-order bits of pixels in an image on the Web.
In this case, let's assume thatit's the daily solution to the DUKE CHRONICLE crossword puzzle:
We might read it diagonally, up and to the right, beginning at the top-left corner: the letter "N."
This would give us the following pseudo-random key: N OI MRP SAE GTNS..."
XXXXX
Polyalphabetic Substitution
A blank grid for encryption, decryption, cryptanalysis and demonstration purposes.
"near an Hundred Alphabets"
The Athenian Mercury (June 1, 1692)
No "j" or "v" is used. No instructions were given.
I count only 24 alphabets! Any ideas what the publishers had in mind?
email me

To encipher the password for a secret meeting.
An early labor organization.

A) Coshocton 1907 Encrypted Post Card
Hints for decipherment.
B) Carthage 1907 Encrypted Post Card
C) Cobleskill 1906 Encrypted Post Card
D) Santa Clara June 25 Encrypted Post Card
E) Neuchatel Swiss Encrypted Post Card
F) Hanford Encrypted Post Card
G) Kingston Encrypted Post Card
H) Toledo Encrypted Post Card
I) Gray Encrypted Post Card
J) London Encrypted Post Card
K) Tepi 17 Encrypted Post Card
L) Tepi 25 Encrypted Post Card
M) Newcastle Encrypted Post Card
N) Ormond Beach Encrypted Post Card (addressed to Briggs as in "O").
O) Paso Robles Encrypted Post Card (addressed to Briggs as in "N").