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Modulo Cipher

Tool to decrypt/encrypt with modulo. Modulo calculations applied on numbers can make possible ciphering using the calculated values.

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Modulo Cipher -

Tag(s) : Homophonic Substitution Cipher

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# Modulo Cipher

## Answers to Questions (FAQ)

### How to encrypt using Modulo cipher?

Modulo Cipher Encryption uses modular arithmetics and a sequence of numbers, characters must be converted into numbers, e.g. A=1, B=2, ... Z=26, but any numeric conversion (like the ASCII table) is fine.

Example: To crypt DCODE with the modulo 26, convert the text to numbers 4,3,15,4,5.

For each number to encrypt, calculate a random number which value is equal to the number to crypt.

Example: For $4$, take $654$, as $654 \equiv 4 \ mod 26$
For $3$, take $965$, as $965 \equiv 3 \ mod 26$.
The encrypted message is 654,965,561,732,941 (many other cipher message are possible)

### How to decrypt Modulo cipher?

Decryption requires to know the value of the Modulo and to know the series of number to decrypt.

Example: The encrypted message is 654,965,561,732,941with the modulo 26.

For each number N, calculate the value of the remainder in the euclidean division of N by the modulo to get the plain number.

Example: The plain text is 4,3,15,4,5, that can be translate into DCODE with A=1, B=2, ...

### How to recognize Modulo ciphertext?

The ciphered message is constituted of somehow large random numbers.

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

The Affine cipher use modulo in the calculation $C = a \times P + b \ mod 26$

## Source code

dCode retains ownership of the online 'Modulo Cipher' tool source code. Except explicit open source licence (indicated CC / Creative Commons / free), any 'Modulo Cipher' algorithm, applet or snippet (converter, solver, encryption / decryption, encoding / decoding, ciphering / deciphering, translator), or any 'Modulo Cipher' function (calculate, convert, solve, decrypt / encrypt, decipher / cipher, decode / encode, translate) written in any informatic language (Python, Java, PHP, C#, Javascript, Matlab, etc.) and no data download, script, copy-paste, or API access for 'Modulo Cipher' will be for free, same for offline use on PC, tablet, iPhone or Android ! dCode is free and online.

## Need Help ?

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

## Questions / Comments

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

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