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Homophonic Cipher

Tool to decrypt / encrypt by homophonic substitution. The homophonic number consists of replacing each letter of the alphabet by several substitutes in order to prevent cryptanalysis by frequency analysis.

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Homophonic Cipher -

Tag(s) : Homophonic Substitution Cipher

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Homophonic Cipher

Homophonic Decoder




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Homophonic Encoder



Tool to decrypt / encrypt by homophonic substitution. The homophonic number consists of replacing each letter of the alphabet by several substitutes in order to prevent cryptanalysis by frequency analysis.

Answers to Questions

How to encrypt using Homophonic cipher?

The homophonic substitution cipher uses a correspondence table between the letters / characters of the plain message and one or more letters / numbers / groups of characters. Consequently, the same letter may have several possible encryption and the same message will possibly have several possible encrypted versions.

The objective aimed at by the use of several correspondences for the letters of the plain message is to prevent an attack by frequency analysis, possible on mono-alphabetic (and also polyalphabetic) substitutions. Consequently, it is clever to use a number of correspondence per letter proportional to the frequency of the letter in the language of the plain message.

Example: ABC is coded with multiple matches: A(45,96,17), B(37,60), C(05,88) as 45,60,88 or 96,60,05 or 96,37,05 etc.

In order to simplify the work of the message receiver, use groups of numbers / letters of fixed length (here 2 digits).

How to decrypt an Homophonic cipher?

Use the correspondence table to transform each character / group of characters in the plain message.

Example: '34,25,10 'has been coded with these multiple correspondances: A(87,34,11), B(25,80), C(10,55), the plain message is ABC

How many correspondances to use per letters?

By taking 100 numbers, the ideal match is approximately equal to the frequency of each letter in the English language (expressed as a percentage rounded to the nearest unit)

E12T9A8O7
I7N7S6H6
R6L4D4C2
U2M2W2F2
G2Y2P2B2
V1K1J1X1
Q1Z1

Using the pieces of a Scrabble game is a good idea.

How to recognize an homophonic ciphertext?

Well done, the frequency of characters in a homophonically encrypted message is close to that of a perfectly random text, its index of coincidence too.

How to decipher homophonic without correspondance table?

If the correspondances are proportional to the frequency of characters in the language of the plain message, then it is impossible to use frequency analysis or coincidence index techniques.

From a portion of known or assumed text, it is possible to guess a few correspondences of some characters but it is often insufficient to decipher the whole message.

Source code

dCode retains ownership of the source code of the script Homophonic 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 released for free. To download the online Homophonic Cipher script for offline use on PC, iPhone or Android, ask for price quote on contact page !

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Thanks to your feedback and relevant comments, dCode has developped the best Homophonic Cipher tool, so feel free to write! Thank you !


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