Search for a tool
Mono-alphabetic Substitution

Tool to decrypt monoalphabetical substitution and find each letter of a substituted message with a deranged alphabet (monoalphabetic cipher).

Results

Mono-alphabetic Substitution -

Tag(s) : Substitution Cipher

Share
dCode and more

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!

Please, check our dCode Discord community for help requests!
NB: for encrypted messages, test our automatic cipher identifier!

Thanks to your feedback and relevant comments, dCode has developed the best 'Mono-alphabetic Substitution' tool, so feel free to write! Thank you!

# Mono-alphabetic Substitution

## Custom Deranged Alphabet Generator

### How to encrypt using an alphabetical substitution?

The monoalphabetical substitution consists in using a mixed alphabet (with the letters in an unusual order) and replacing the letters of the alphabet normal by it.

Example: NBAJYFOWLZMPXIKUVCDEGRQSTH is a totally random alphabet with the 26 letters of the Latin alphabet.

To understand, write the alphabet over the classic alphabet:

Plain alphabet ABCDEFGHIJKLMNOPQRSTUVWXYZ NBAJYFOWLZMPXIKUVCDEGRQSTH

The substitution involves a replacement the plaintext of all the letters of the first row with the letters associated with the second row.

Example: All A become N, all the B remain B, all the C become A, etc.

Example: With this substitution DCODE is encrypted as JAKJY.

Any deranged alphabet can be used to create a single alphabetical substitution (the same letter can be used only once in the alphabet).

### How to decrypt using an alphabetical substitution?

Decryption requires knowing the alphabet mixed used and the inverse substitution encryption.

Substitution Alphabet NBAJYFOWLZMPXIKUVCDEGRQSTH ABCDEFGHIJKLMNOPQRSTUVWXYZ

The substitution involves replacing in the ciphertext all the letters of the first row with the letters associated with the second row.

Example: The encrypted message JAKJY has for plain message DCODE.

### How to recognize a mono alphabetical substituted text?

The ciphered message has an index of coincidence identical to the language of the plain text.

English speakers call this encryption aristocrat (if there are spaces) or patristocrat (if there are no spaces between words).

### How to decipher a substitution without the alphabet?

The interactive tool provided by dCode allows a semi-automatic decryption of messages encrypted by substitution ciphers.

The main technique is to analyze the frequencies of letters and find the most likely bigrams.

The known plaintext attack makes it possible to deduce some letters of the alphabet via the knowledge or the preliminary guess of certain portions of the plain text.

Example: The most common alphabets used for substitutions are: AZERTYUIOPQSDFGHJKLMWXCVBN
NBVCXWMLKJHGFDSQPOIUYTREZA
QWERTYUIOPASDFGHJKLZXCVBNM
MNBVCXZLKJHGFDSAPOIUYTREWQ
AQWZSXEDCRFVTGBYHNUJIKOLPM
ZYXWVUTSRQPONMLKJIHGFEDCBA
'AEIOUYBCDFGHJKLMNPQRSTVWXZ

### What are the variants of the substitution cipher?

First, some substitution use specific alphabets, as Atbash that takes the alphabet backwards ZYXWVUTSRQPONMLKJIHGFEDCBA or the Caesar cipher which uses a shifted alphabet DEFGHIJKLMNOPQRSTUVWXYZABC that is shifted by 3. Then there are substitutions that use several alphabets, such as alphabet that changes depending on an algorithm defined by encryption (e.g. Vigenere uses 26 alphabets).

In game-play journals, substitution games / exercises are often called cryptograms.

## Source code

dCode retains ownership of the "Mono-alphabetic Substitution" source code. Except explicit open source licence (indicated Creative Commons / free), the "Mono-alphabetic Substitution" algorithm, the applet or snippet (converter, solver, encryption / decryption, encoding / decoding, ciphering / deciphering, translator), or the "Mono-alphabetic Substitution" functions (calculate, convert, solve, decrypt / encrypt, decipher / cipher, decode / encode, translate) written in any informatic language (Python, Java, PHP, C#, Javascript, Matlab, etc.) and all data download, script, or API access for "Mono-alphabetic Substitution" are not public, same for offline use on PC, mobile, tablet, iPhone or Android app!
Reminder : dCode is free to use.

## Cite dCode

The copy-paste of the page "Mono-alphabetic Substitution" or any of its results, is allowed as long as you cite dCode!
Cite as source (bibliography):
Mono-alphabetic Substitution on dCode.fr [online website], retrieved on 2022-08-08, https://www.dcode.fr/monoalphabetic-substitution

## Need Help ?

Please, check our dCode Discord community for help requests!
NB: for encrypted messages, test our automatic cipher identifier!