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Caesar Cipher

Tool to decrypt/encrypt with Caesar. Caesar cipher (or Caesar code) is a shift cipher, one of the most easy and most famous encryption system. It uses the substitution of a letter by another one further in the alphabet.

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Caesar Cipher -

Tag(s) : Cryptography,Substitution Cipher

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Caesar Cipher

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Tool to decrypt/encrypt with Caesar. Caesar cipher (or Caesar code) is a shift cipher, one of the most easy and most famous encryption system. It uses the substitution of a letter by another one further in the alphabet.

Answers to Questions

How to encrypt using Caesar cipher?

Encryption with Caesar code is a simple substitution (one letter replaces another). Caesar code remplace is with an alphabet shift : a letter further in the alphabet.

One wants to crypt DCODEX with a shift of 3

To encrypt D, one takes the alphabet and look 3 letters after : G. So D is crypted with G.

To encrypt X, one must loop the alphabet : after X : Y, after Y : Z, after Z : A. So X is crypted A.

Another way to crypt, more mathematical, one can note A = 0, B = 1, ..., Z = 25, and add a constant (the shift), then the result modulo 26href (alphabet length) is the coded text.

D = 4, 4+3 = 7 and 7 = G, so D is crypted with G

X = 23, 23+3 = 26 and 26 mod 26 = 0, 0 = A, so X is crypted with A, etc.

DCODEX becomes GFRGHA

How to decrypt Caesar cipher?

Caesar code decryption replaces a letterhref another with an inverse alphabet shift : a previous letter in the alphabet.

One wants to de crypt GFRGHA with a shift of 3

To decrypt G, one takes the alphabet and look 3 letters before : D. So G is decrypted with D.

To decrypt X, one must loop the alphabet : before A : Z, before Z : Y, before Y : X. So A is decrypted X.

Another way to de crypt, more mathematical, one can note A = 0, B = 1, ..., Z = 25, and substract a constant (the shift), then the result modulo 26href (alphabet length) is the plain text.

G = 7, 7-3 = 4 and 4 = D, so G is decrypted with D

A = 0, 0-3 = -3 and -3 mod 26 = 23, 23 = X, so A is decrypted with X, etc.

GFRGHA becomes DCODEX.

How to recognize Caesar ciphered text?

A shifted ciphered message have an indice of coincidence similar to the language of the plain text.

How to decipher Caesar without knowing the shift?

The easiest method consist in testing all shifts, if the alphabet has 26 letters, it takes only 25 tries.

What are the variants of the Caesar cipher?

Caesar cipher is best known with a shift of 3, all other shifts are possible. Some shifts are known with other cipher names.

Another variant changes the alphabet, an can introduce letters for example.

Why the name Caesar Cipher?

Caesar used this technique for comme correspondances, especially military, for example with Ciceron (shift of 3).

What is August Cipher?

August Cipher is the name given to Caesar Cipher with a shift of 1.

What are other Caesar Cipher names?

Helene code, L = N, the shift is 2

Eiffel code, F = L, the shift is 6

WC code, W = C, the shift is 6

ROT13href code, the shift is 13 and reversible

ROT5href code for digits, the shift is 5 and reversible

ROT47href code for ASCIIhref, the shift is 47 and reversible

How to cipher CAESAR with the Caesar code?

DBFTBS, ECGUCT, FDHVDU, GEIWEV, HFJXFW, IGKYGX, JHLZHY, KIMAIZ, LJNBJA, MKOCKB, NLPDLC, OMQEMD, PNRFNE, QOSGOF, RPTHPG, SQUIQH, TRVJRI, USWKSJ, VTXLTK, WUYMUL, XVZNVM, YWAOWN, ZXBPXO, AYCQYP, BZDRZQ

When Caesar Cipher have been invented ?

Unknown, but Caesar is born in 100 before JC

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Source code

dCode retains ownership of the source code of the script Caesar Cipher. Except explicit open source licence (free / freeware), any algorithm, applet, software (converter, solver, encryption / decryption, encoding / decoding, ciphering / deciphering, translator), or any snippet or function (convert, solve, decrypt, encrypt, decipher, cipher, decode, code, translate) written in PHP (or Java, C#, Python, Javascript, etc.) which dCode owns rights can be transferred after sales quote. So if you need to download the Caesar Cipher script for offline use, for you, your company or association, see you on contact page !

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