On the Subject of the Alberti CM

A machine that knows no bounds when it comes to ciphers.

Turn the letter on screen A to a Value via the Value Table. This is your Alberti Offset, you can freely modulo this offset by 26.

If the Submit Button is white, follow the instructions under Encrypt Instructions. Otherwise follow the instructions under Decrypt Instructions.

Encrypt Instructions

  • Take the sum of the alphabetic position (A1Z26) of the Nth letter of the encrypted word and the Alberti Offset.
  • If the resulting number is above 26, subtract 26 until the number is between 1 - 26.
  • Turn the number back into a letter to get your Nth decrypted letter (A1Z26).
  • Add the number on screen 1 to the Alberti Offset, freely being able to modulo the result by 26. This is your new Alberti Offset.

Decrypt Instructions

  • Take the alphabetic position (A1Z26) of the Nth letter of the encrypted word and subtract it by the Alberti Offset.
  • If the resulting number is below 1, add 26 until the number is between 1 - 26.
  • Turn the number back into a letter to get your Nth decrypted letter (A1Z26).
  • Add the number on screen 1 to the Alberti Offset, freely being able to modulo the result by 26. This is your new Alberti Offset.

Example 1

Encrypted Word: UDZL
Alberti Offset: A → 2
Screen 1: 21
Using Encrypt Rules

U + 2 → 21 + 2 → 23 → W
2 + 21 → 23
D + 23 → 4 + 23 → 27 - 26 → 1 → A
23 + 21 → 44 - 26 → 18
Z + 18 → 26 + 18 → 44 - 26 → 18 → R
18 + 21 → 39 - 26 → 13
L + 13 → 12 + 13 → 25 → Y

Decrypted Word: WARY

Example 2

Encrypted Word: QJSJSW
Alberti Offset: V → 102 MOD 26 → 24
Screen 1: 17
Using Decrypt Rules

Q - 24 → 17 - 24 → -7 + 26 → 19 → S
24 + 17 → 41 - 26 → 15
J - 15 → 10 - 15 → -5 + 26 → 21 → U
15 + 17 → 32 - 26 → 6
S - 6 → 19 - 6 → 13 → M
6 + 17 → 23
J - 23 → 10 - 23 → -13 + 26 → 13 → M
23 + 17 → 40 - 26 → 14
S - 14 → 19 - 14 → 5 → E
14 + 17 → 31 - 26 → 5
W - 5 → 23 - 5 → 18 → R

Decrypted Word: SUMMER

You can use this table as a way to get your decrypted letters. To do so, follow the instructions below:

  • Use the Alberti Offset as the row.
  • If you are adding, use the encrypted word's letter as the column. The intersection of the 2 will be your decrypted letter.
  • If you are subtracting, find the encrypted word's letter within the row. The column that the letter is in becomes your decrypted letter.
ABCDEFGHIJKLMNOPQRSTUVWXYZ
0ABCDEFGHIJKLMNOPQRSTUVWXYZ
1BCDEFGHIJKLMNOPQRSTUVWXYZA
2CDEFGHIJKLMNOPQRSTUVWXYZAB
3DEFGHIJKLMNOPQRSTUVWXYZABC
4EFGHIJKLMNOPQRSTUVWXYZABCD
5FGHIJKLMNOPQRSTUVWXYZABCDE
6GHIJKLMNOPQRSTUVWXYZABCDEF
7HIJKLMNOPQRSTUVWXYZABCDEFG
8IJKLMNOPQRSTUVWXYZABCDEFGH
9JKLMNOPQRSTUVWXYZABCDEFGHI
10KLMNOPQRSTUVWXYZABCDEFGHIJ
11LMNOPQRSTUVWXYZABCDEFGHIJK
12MNOPQRSTUVWXYZABCDEFGHIJKL
13NOPQRSTUVWXYZABCDEFGHIJKLM
14OPQRSTUVWXYZABCDEFGHIJKLMN
15PQRSTUVWXYZABCDEFGHIJKLMNO
16QRSTUVWXYZABCDEFGHIJKLMNOP
17RSTUVWXYZABCDEFGHIJKLMNOPQ
18STUVWXYZABCDEFGHIJKLMNOPQR
19TUVWXYZABCDEFGHIJKLMNOPQRS
20UVWXYZABCDEFGHIJKLMNOPQRST
21VWXYZABCDEFGHIJKLMNOPQRSTU
22WXYZABCDEFGHIJKLMNOPQRSTUV
23XYZABCDEFGHIJKLMNOPQRSTUVW
24YZABCDEFGHIJKLMNOPQRSTUVWX
25ZABCDEFGHIJKLMNOPQRSTUVWXY

Alternative Method

The key below will be referred to as the Alberti Key:

ABCDEFGHIJKLMNOPQRSTUVWXYZ
ABCDEFGHIJKLMNOPQRSTUVWXYZ

Turn the letter on screen A to a Value via the Value Table, modulo 26. Shift the bottom row of the Alberti Key to the left that many times.

If the Submit Button is white, follow the instructions under Encrypt Instructions. Otherwise follow the instructions under Decrypt Instructions.

Encrypt Instructions

  • Find the Nth letter of the encrypted word in the top row of the Alberti Key.
  • Replace it with the letter directly below it to get your Nth decrypted word.
  • Shift the bottom row of the Alberti Key to the left X times where X is equal to the number displayed on screen 1.

Decrypt Instructions

  • Find the Nth letter of the encrypted word in the bottom row of the Alberti Key.
  • Replace it with the letter directly above it to get your Nth decrypted word.
  • Shift the bottom row of the Alberti Key to the left X times where X is equal to the number displayed on screen 1.

Example 1

Encrypted Word: UDZL
Alberti Offset: A → 2
Screen 1: 21
Using Encrypt Rules

ABCDEFGHIJKLMNOPQRSTUVWXYZ
CDEFGHIJKLMNOPQRSTUVWXYZAB

U → W

ABCDEFGHIJKLMNOPQRSTUVWXYZ
XYZABCDEFGHIJKLMNOPQRSTUVW

D → A

ABCDEFGHIJKLMNOPQRSTUVWXYZ
STUVWXYZABCDEFGHIJKLMNOPQR

Z → R

ABCDEFGHIJKLMNOPQRSTUVWXYZ
NOPQRSTUVWXYZABCDEFGHIJKLM

L → Y

Decrypted Word: WARY

Example 2

Encrypted Word: QJSJSW
Alberti Offset: V → 102 MOD 26 → 24
Screen 1: 17
Using Decrypt Rules

ABCDEFGHIJKLMNOPQRSTUVWXYZ
YZABCDEFGHIJKLMNOPQRSTUVWX

Q → S

ABCDEFGHIJKLMNOPQRSTUVWXYZ
PQRSTUVWXYZABCDEFGHIJKLMNO

J → U

ABCDEFGHIJKLMNOPQRSTUVWXYZ
GHIJKLMNOPQRSTUVWXYZABCDEF

S → M

ABCDEFGHIJKLMNOPQRSTUVWXYZ
XYZABCDEFGHIJKLMNOPQRSTUVW

J → M

ABCDEFGHIJKLMNOPQRSTUVWXYZ
OPQRSTUVWXYZABCDEFGHIJKLMN

S → E

ABCDEFGHIJKLMNOPQRSTUVWXYZ
FGHIJKLMNOPQRSTUVWXYZABCDE

W → R

Decrypted Word: SUMMER