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READLATR.DOC USA-CRYPTO V1.1 08/01/93
This document contains additional information about ciphers and
USA-CRYPTO screens.
ABOUT CRYPTOGRAPHY & USA-CRYPTO:
Cryptography is the art (and science) of writing and reading in
secret. It includes special signs, drawings, special inks &
paper, coding methods, and mechanical & electronic devices; all
for making written communications difficult for unauthorized
reading. Shortly after creation of the written word,
cryptography was invented; to make secure the written
communications of governments, armies, statesmen, rulers and
revolutionaries.
On a more basic level, many enjoy the challenge of solving
puzzles (in newspapers & magazines) referred to as cryptograms
(or more exactly substitution ciphers).
While PC's have the power to solve ciphers all by themselves,
that's no fun. USA-CRYPTO is a DOS based, PC system which
helps a decoder (a person) to find the solution, making this
challenging task easier and more fun. Using USA-CRYPTO is
fairly intuitive; you just substitute solution characters
(plaintext) in any position above the code (ciphertext).
USA-CRYPTO is a tool and a game. Cryptograms from another
source (magazines, newspapers, spies, foreign agents, etc.) can
be entered as CIPHERTEXT into USA-CRYPTO using the keyboard,
and worked out to provide the plaintext solution.
USA-CRYPTO also includes a database of ready-to-solve ciphers
to eliminate the task of typing the ciphertext (a job where the
two finger method is sometimes better than a skilled typist).
USA-CRYPTO maintains statistics on each cipher in these
Cipherfiles.
All the ciphers in the database have a 1-to-1 relationship
between ciphertext and plaintext characters. Also each cipher
character never equals the same plaintext character ('A' never
equals 'A', etc). Only the 26 uppercase alphabet characters
are substituted. All punctuation is presented in both cipher &
plain texts.
USA-CRYPTO runs an elapsed timer during any cipher. When a
database cipher is solved in less than the current record time,
the database is updated with the Best Solution Time, and the
Decoder's Id (initials).
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READLATR.DOC USA-CRYPTO V1.1 08/01/93
ABOUT CIPHERS:
For our purposes, a cryptogram or cipher starts with a message
written in clear uppercase English (referred to as PLAINTEXT).
As an example:
UNICORNS USED THE UNICYCLES. <-- PLAINTEXT
The cipher is created by substituting other letters for those
in the plaintext. For example, for each occurrence of a 'U',
substitute 'A'
A_______ A___ ___ A________. <-- CIPHER (in progress)
UNICORNS USED THE UNICYCLES. <-- PLAINTEXT
Continue with N->B, I->T, C->W, E->M, S->Y, L->E to get:
ABTW__BY AYM_ __M ABTW_WEMY. <-- CIPHER (in progress)
UNICORNS USED THE UNICYCLES. <-- PLAINTEXT
Finishing up with O->Q, R->P, D->G, T->O, H->X, and Y->N.
ABTWQPBY AYMG OXM ABTWNWEMY. <-- CIPHER (completed)
Rare is the decoder who looking at the above line immediately
thinks of unicorns and unicycles. But with a little trial and
error, brainpower, inspiration, and persistence, the solution
set ('A'='U', 'N'='B', etc.) can be found.
Most of the ciphers in the database are quotes much longer than
the above cipher. With longer ciphers, and more characters,
the frequencies of letters and words make solutions simpler.
USA-CRYPTO KEYBOARD ENTRY:
There is a ready stream of cryptograms to be obtained from
newspapers, magazines, the CIA, etc. The keyboard entry screen
allows entry of the coded (ciphertext) message.
Keyboard entry of ciphers is a typing teachers 'dream test'.
Normal typists screech to a near stop when typing nonsense
syllables like:
"QEB NRFZH YOLTK CLU GRJMBA LSBO QEB IXWV ALD"
(the quick brown fox jumped over the lazy dog)
Some special keys to make keyboard cipher entry easier:
<F6> - erases the current line.
<SH><F6> - erases from the cursor to the end of the
current line.
<F8> - goes to the next line.
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READLATR.DOC USA-CRYPTO V1.1 08/01/93
<Enter> - goes to the next line.
<Tab> - goes to the next line.
<SH><Tab> - goes to the previous line.
<Home> - moves cursor to the left margin.
<End> - moves cursor to the right margin.
<Insert> - toggles the cursor between '_' (typeover
mode) and '▄' (insert mode).
<Delete> - deletes the cursor character and shifts the
remainder of the line to the left.
<Backspace> - deleted the character to the left of the
cursor, and shifts the remainder of the line
one space to the left.
<F5> - Saves the entry back to the decoder screen.
If you discover a typo while working in the decoder screen, re-
select <F5>, make the correction, and re-save. The elapsed
time counter is reset, and you can restart the cipher.
DECODER SCREEN:
This is the main processing screen of USA-CRYPTO. Entry of a
plaintext character on any of the 7 plaintext [RED, upper]
lines fills them into all corresponding plaintext positions.
Entry of a space, fills space into all corresponding plaintext
positions.
╔═[USA-CRYPTO]══════════════════════════
║
PLAINTEXT─┬───> ║ Plaintext DEFGHIJKLMNOPQRSTUVWXYZABC
LINES │ ╔═> ║ Cipher ABCDEFGHIJKLMNOPQRSTUVWXYZ
│ ║ ║ Unused
│ ║ ║
├───> ║ IS LIFE SO DEAR, OR PEACE SO SWEET,
│ ╠═> ║ FP IFCB PL ABXO, LO MBXZB PL PTBBQ,
│ ║ ║
├───> ║ AS TO BE PURCHASED AT THE PRICE OF CHA
│ ╠═> ║ XP QL YB MROZEXPBA XQ QEB MOFZB LC ZEX
│ ║ ║
├───> ║ FORBID IT, ALMIGHTY GOD! I KNOW NOT W
CIPHER════│═╬═> ║ CLOYFA FQ, XIJFDEQV DLA! F HKLT KLQ T
LINES │ ║ ║
Some function keys available on this screen are:
<F3> allows all the plaintext (solution) to be cleared
(for when you just want to wipe it all away and start
all over).
<F5> allows input of a new cipher from the CRYPTO database
or from the keyboard.
<F7> displays a window showing the frequencies of all the
ciphertext characters.
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READLATR.DOC USA-CRYPTO V1.1 08/01/93
For ciphers retrieved from the database, <F9> will display a
hint for the character substitution at the cursor location.
And just like buying vowels from Vanna White on 'Wheel of
Fortune', USA-CRYPTO extracts a price of 30 seconds of elapsed
time.
Entry of the correct solution of the database ciphers (in
record time), updates statistical data on the cipher's record.
CIPHER INPUT SELECTION SCREEN:
This window allows input selection of the cipher. The window
comes up with the radio button set in the position last
selected.
The <Tab> or arrow keys allow movement of the radio button to
CRYPTO database or Keyboard Entry. After moving to your
selection, <Enter> brings up the corresponding entry window.
DATABASE INPUT WINDOW:
This window allows selection of a cipher from the CRYPTO
database.
To solve a particular cipher (one you may not have completed
earlier), enter the number of the cipher. Otherwise, <Enter>
with no number, will retrieve the least recently accessed
cipher (earliest played date).
For either cipher, the screen returns statistics about the
cipher (but not the solution), and prompts "Continue [y/n]?".
<N> returns to the window for re-entry of the cipher number.
<Y> returns to the decoder screen with the cipher text filled
in, and the elapsed timer started.
<Esc> from any window, returns to the decoder screen.
DATABASE UPDATE WINDOW:
This window appears after a CRYPTO database cipher has been
decrypted in less time than the previous (stored) best time.
The new elapsed time is stored.
This window prompts for the id (initials) of the decoder.
After entry, the screen prompts "Continue [y/n]?". <N> returns
to the window for re-entry of the ID. <Y> stores the Id, and
updates the record.
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READLATR.DOC USA-CRYPTO V1.1 08/01/93
FREQUENCY WINDOW:
This window shows the frequency of the cipher characters. High
frequency characters would include plaintext {E, T, A, O, I, N}
and low frequencies would include plaintext {K, X, J, Q, Z}.
Although not related to the single character frequency window,
other most common short words would be:
1 character - {A, I}
2 character - {OF, TO, IN, AS, IS, BE}
3 character - {THE, AND, YOU, FOR, WAS}
4 character - {THAT, WILL, HAVE, WITH}
5 character - {WHICH, WOULD, THERE}
<F7> or <Esc> returns to the decoder screen.
*** END OF READLATR.DOC ***
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