Tool to decrypt/encrypt Alberti. The Alberti cipher is a polyalphabetic cipher system that uses two mobile concentric disks which can rotate.

Alberti Cipher - dCode

Tag(s) : Poly-Alphabetic Cipher

dCode is free and its tools are a valuable help in games, maths, geocaching, puzzles and problems to solve every day!

A suggestion ? a feedback ? a bug ? an idea ? *Write to dCode*!

> [**News**]: Discover the next version of dCode Alberti Cipher!

Sponsored ads

Tool to decrypt/encrypt Alberti. The Alberti cipher is a polyalphabetic cipher system that uses two mobile concentric disks which can rotate.

Encryption uses a disk with two alphabets. By rotating a disk, it shifts an alphabet to the next letter.

To encrypt, the disk is set in one position, the initial shift (which can be zero) corresponds to the number of letters shifted at the beginning.

Example: The disk is composed of ABCDEFGHIJKLMNOPQRSTUVWXYZ for the large outer ring, and abcdefghijklmnopqrstuvwxyz for the small inner ring. A is in line with a, B is inline with b, etc. Rotating a disk by 2, then A is in line with c, and the initial shift becomes 2.

Each letter of the plain text found on the outer ring, is replaced by the corresponding one (the one aligned) in the inner ring.

By default, every 4 characters (4 = period), the disk is rotated clockwise of 1 letter (1 = periodic increment), this changes the substituting alphabet.

Example: Encrypt DCODE with the parameters: initial shift: 1, periodic increment: 2, period: 3.

Alphabets are such as ABCDEFGHIJKLMNOPQRSTUVWXYZ is aligned with bcdefghijklmnopqrstuvwxyza.

The period begins, D is coded by e, C by d, O by p, the period (length 3) ends, the disk is rotated by 2 letters.

Alphabets are now aligned like this : ABCDEFGHIJKLMNOPQRSTUVWXYZ with defghijklmnopqrstuvwxyzabc, the new period begins, etc.

The crypted message is edpgh

Le decryption needs the disk (or the 2 alphabets) and the parameters: initial position, period and shift.

To cipher a message, the disk is set with the corresponding initial shift. Each letter is identified on the inner disk, and is coded by the letter aligned in the outer disk.

By default, every 4 characters (4 = period), the disk is rotated counter-clockwise of 1 letter (1 = periodic increment).

Example: The parameters are: initial shift: 1, periodic increment: 2, period: 3, and the cipher message edpgh.

Alphabets are such as ABCDEFGHIJKLMNOPQRSTUVWXYZ is aligned with bcdefghijklmnopqrstuvwxyza

The period begins, e is decoded by D, d by C, p by O, the period (length 3) ends, the disk is rotated by 2 letters.

Alphabets are now aligned like this: ABCDEFGHIJKLMNOPQRSTUVWXYZ with defghijklmnopqrstuvwxyzabc, the new period begins, etc.

The original plain text is DCODE

The ciphered message has a polyalphabetic index of coincidence.

In its original version, the message has only these letters: ABCDEFGHIKLMNOPQRSTVXYZ and &, no J, U or W

One can crack Alberti but brute-forcing the period first, then initial shift and periodic increment. Use the 'Bruteforce attack' button.

Around 1460.

dCode retains ownership of the source code of the script Alberti Cipher online. Except explicit open source licence (indicated Creative Commons / free), any algorithm, applet, snippet, software (converter, solver, encryption / decryption, encoding / decoding, ciphering / deciphering, translator), or any function (convert, solve, decrypt, encrypt, decipher, cipher, decode, code, translate) written in any informatic langauge (PHP, Java, C#, Python, Javascript, Matlab, etc.) which dCode owns rights will not be given for free. To download the online Alberti Cipher script for offline use on PC, iPhone or Android, ask for price quote on contact page !

alberti,disk,wheel,formula,leon,battista,cifris,stabilis,mobilis

Source : https://www.dcode.fr/alberti-cipher

© 2019 dCode — The ultimate 'toolkit' to solve every games / riddles / geocaches. dCode

Feedback

> [

News]: Discover the next version of dCode Alberti Cipher!