[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 one-time-pad cipher found with Ché which was used in this message to Fidel Castro dated May 18, 1967.
Source: David Kahn, KAHN ON CODES, MacMillan, New York (1983).


Ché's "monome-dinome" (single-letter-to-two-digit) table
constructed from the keyword "estadoy" followed by the remainder of the alphabet.
Letters are indexed by row (pink) and column (yellow). Blank cells are used as spaces. Gray cells are never used.
"73" is a letter-to-number switch. "77" is a number-to-letter switch.
Numbers are sent in the clear and repeated three times.


Derivation of the ciphertext from the plaintext ("Leche" is the codename for Fidel).
Plaintext is first converted to numbers using the table above.
The conversion is then added (modulo 10) to the key to give the ciphertext.
Finally, the ciphertext is then grouped into "words" of five digits (not shown).
A Numerically Indexed Alphabetic Table
Which might be changed on a periodic schedule or used only once.
A Candidate for a Quasi-Random Key Hidden in Plain Sight
The sender and receiver may secretly agree in to use widely published material as a daily key.
It might be a newspaper article, pages in a book, or or the low-order bits in an image on the Web.
In our case, let's assume it is the daily solution to the DAILY BRUIN crossword puzzle:
We might read it diagonally, up and to the right, beginning at the top-left corner, the letter "P."
This would give us the quasi-random key "P AI MLC EPN RRAI AOGCC ..."
Polyalphabetic Substitution
A blank grid for 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.

1907 Encripted Coshocton Post Card
Hints for decipherment.
1907 Encripted Carthage Post Card
Swiss Post Card