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

Mono-alphabetic Substitution - dCode

Tag(s) : Substitution Cipher

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⮞ Go to: Deranged Alphabet Generator

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 |
---|---|

Substitution alphabet | 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).

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

Substitution Alphabet | NBAJYFOWLZMPXIKUVCDEGRQSTH |
---|---|

Plain Alphabet | 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`.

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).

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

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.

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Cite as source (bibliography):

*Mono-alphabetic Substitution* on dCode.fr [online website], retrieved on 2022-08-08,

- Monoalphabetic Substitution Decoder
- Monoalphabetic Substitution Encoder
- Custom Deranged Alphabet Generator
- How to encrypt using an alphabetical substitution?
- How to decrypt using an alphabetical substitution?
- How to recognize a mono alphabetical substituted text?
- How to decipher a substitution without the alphabet?
- What are the variants of the substitution cipher?

substitution,monoalphabetical,alphabet,attack,known,plaintext,cryptogram,aristocrat,patristocrat

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