Editing Caesar cipher (section)

{{short description|Simple and widely known encryption technique}}
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[[File:Caesar cipher left shift of 3.svg|thumb|The action of a Caesar cipher is to replace each plaintext letter with a different one a fixed number of places down the alphabet. The cipher illustrated here uses a left shift of 3, so that (for example) each occurrence of {{mono|E}} in the plaintext becomes {{mono|B}} in the ciphertext.]]
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| caption        = Unicorn The action a Caesar cipher is to replace each plaintext letter with a different one a fixed number of places down the alphabet. The cipher illustrated here uses a left shift of three, so that (for example) each occurrence of {{mono|E}} in the plaintext becomes {{mono|B}} in the ciphertext.

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| structure      = [[substitution cipher]]
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| cryptanalysis  = Susceptible to [[frequency analysis]] and brute force attacks.
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In [[cryptography]], a '''Caesar cipher''', also known as '''Caesar's cipher''', the '''shift cipher''', '''Caesar's code''', or '''Caesar shift''', is one of the simplest and most widely known [[encryption]] techniques. It is a type of [[substitution cipher]] in which each letter in the [[plaintext]] is replaced by a letter some fixed number of positions down the [[alphabet]]. For example, with a left shift of 3, {{mono|D}} would be replaced by {{mono|A}}, {{mono|E}} would become {{mono|B}}, and so on.<ref>{{cite web|first = James|last = Smith|work = Golang Project Structure|title = Writing Secret Messages With a Caesar Cipher|url = https://golangprojectstructure.com/caesar-cipher-secret-messages/|date = 2021-11-30|access-date = 2024-10-20}}</ref> The method is named after [[Julius Caesar]], who used it in his private correspondence.

The encryption step performed by a Caesar cipher is often incorporated as part of more complex schemes, such as the [[Vigenère cipher]], and still has modern application in the [[ROT13]] system. As with all single-alphabet substitution ciphers, the Caesar cipher is easily broken and in modern practice offers essentially no [[communications security]].