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Caesar cipher

Caesar cipher, is one of the simplest and most widely known encryption techniques. The transformation can be represented by aligning two alphabets, the cipher alphabet is the plain alphabet rotated left or right by some number of positions.

When encrypting, a person looks up each letter of the message in the 'plain' line and writes down the corresponding letter in the 'cipher' line. Deciphering is done in reverse.
The encryption can also be represented using modular arithmetic by first transforming the letters into numbers, according to the scheme, A = 0, B = 1,..., Z = 25. Encryption of a letter x by a shift n can be described mathematically as

Plaintext: rousse
cipher variations:
spvttf tqwuug urxvvh vsywwi wtzxxj
xuayyk yvbzzl zwcaam axdbbn byecco
czfddp dageeq ebhffr fciggs gdjhht
hekiiu ifljjv jgmkkw khnllx liommy
mjpnnz nkqooa olrppb pmsqqc qntrrd

Decryption is performed similarly,

(There are different definitions for the modulo operation. In the above, the result is in the range 0...25. I.e., if x+n or x-n are not in the range 0...25, we have to subtract or add 26.)
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Atbash Cipher

Atbash is an ancient encryption system created in the Middle East. It was originally used in the Hebrew language.
The Atbash cipher is a simple substitution cipher that relies on transposing all the letters in the alphabet such that the resulting alphabet is backwards.
The first letter is replaced with the last letter, the second with the second-last, and so on.
An example plaintext to ciphertext using Atbash:
Plain: rousse
Cipher: ilfhhv

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Baconian Cipher

To encode a message, each letter of the plaintext is replaced by a group of five of the letters 'A' or 'B'. This replacement is done according to the alphabet of the Baconian cipher, shown below.
a   AAAAA   g    AABBA     m    ABABB   s    BAAAB     y    BABBA
b   AAAAB   h    AABBB     n    ABBAA   t    BAABA     z    BABBB
c   AAABA   i    ABAAA     o    ABBAB   u    BAABB 
d   AAABB   j    BBBAA     p    ABBBA   v    BBBAB
e   AABAA   k    ABAAB     q    ABBBB   w    BABAA
f   AABAB   l    ABABA     r    BAAAA   x    BABAB

Plain: rousse

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Affine Cipher
In the affine cipher the letters of an alphabet of size m are first mapped to the integers in the range 0..m - 1. It then uses modular arithmetic to transform the integer that each plaintext letter corresponds to into another integer that correspond to a ciphertext letter. The encryption function for a single letter is

where modulus m is the size of the alphabet and a and b are the key of the cipher. The value a must be chosen such that a and m are coprime.
Considering the specific case of encrypting messages in English (i.e. m = 26), there are a total of 286 non-trivial affine ciphers, not counting the 26 trivial Caesar ciphers. This number comes from the fact there are 12 numbers that are coprime with 26 that are less than 26 (these are the possible values of a). Each value of a can have 26 different addition shifts (the b value) ; therefore, there are 12*26 or 312 possible keys.
Plaintext: rousse
cipher variations:

The decryption function is

where a - 1 is the modular multiplicative inverse of a modulo m. I.e., it satisfies the equation

The multiplicative inverse of a only exists if a and m are coprime. Hence without the restriction on a decryption might not be possible. It can be shown as follows that decryption function is the inverse of the encryption function,

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ROT13 Cipher
Applying ROT13 to a piece of text merely requires examining its alphabetic characters and replacing each one by the letter 13 places further along in the alphabet, wrapping back to the beginning if necessary. A becomes N, B becomes O, and so on up to M, which becomes Z, then the sequence continues at the beginning of the alphabet: N becomes A, O becomes B, and so on to Z, which becomes M. Only those letters which occur in the English alphabet are affected; numbers, symbols, whitespace, and all other characters are left unchanged. Because there are 26 letters in the English alphabet and 26 = 2 * 13, the ROT13 function is its own inverse:

ROT13(ROT13(x)) = x for any basic Latin-alphabet text x

An example plaintext to ciphertext using ROT13:

Plain: rousse
Cipher: ebhffr

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Polybius Square

A Polybius Square is a table that allows someone to translate letters into numbers. To give a small level of encryption, this table can be randomized and shared with the recipient. In order to fit the 26 letters of the alphabet into the 25 spots created by the table, the letters i and j are usually combined.
1 2 3 4 5
1 A B C D E
2 F G H I/J K
3 L M N O P
4 Q R S T U
5 V W X Y Z

Basic Form:
Plain: rousse
Cipher: 244354343451

Extended Methods:
Method #1

Plaintext: rousse
method variations:

Method #2
Bifid cipher
The message is converted to its coordinates in the usual manner, but they are written vertically beneath:
r o u s s e 
2 4 5 3 3 5 
4 3 4 4 4 1 
They are then read out in rows:
Then divided up into pairs again, and the pairs turned back into letters using the square:
Plain: rousse
Cipher: rpxotd

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Method #3

Plaintext: rousse
method variations:
txooyf xooyft ooyftx
oyftxo yftxoo ftxooy

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Permutation Cipher
In classical cryptography, a permutation cipher is a transposition cipher in which the key is a permutation. To apply a cipher, a random permutation of size E is generated (the larger the value of E the more secure the cipher). The plaintext is then broken into segments of size E and the letters within that segment are permuted according to this key.
In theory, any transposition cipher can be viewed as a permutation cipher where E is equal to the length of the plaintext; this is too cumbersome a generalisation to use in actual practice, however.
The idea behind a permutation cipher is to keep the plaintext characters unchanged, butalter their positions by rearrangement using a permutation
This cipher is defined as:
Let m be a positive integer, and K consist of all permutations of {1,...,m}
For a key (permutation) , define:
The encryption function
The decryption function
A small example, assuming m = 6, and the key is the permutation :

The first row is the value of i, and the second row is the corresponding value of (i)
The inverse permutation, is constructed by interchanging the two rows, andrearranging the columns so that the first row is in increasing order, Therefore, is:

Total variation formula:

e = 2,718281828 , n - plaintext length

Plaintext: rousse

all 720 cipher variations:
rousse rouses rousse rouses rouess rouess rosuse rosues rossue rosseu rosesu
roseus rossue rosseu rosuse rosues roseus rosesu roessu roesus roessu roesus
roeuss roeuss ruosse ruoses ruosse ruoses ruoess ruoess rusose rusoes russoe
russeo ruseso ruseos russoe russeo rusose rusoes ruseos ruseso ruesso ruesos
ruesso ruesos rueoss rueoss rsuose rsuoes rsusoe rsuseo rsueso rsueos rsouse
rsoues rsosue rsoseu rsoesu rsoeus rssoue rssoeu rssuoe rssueo rsseuo rsseou
rseosu rseous rsesou rsesuo rseuso rseuos rsusoe rsuseo rsuose rsuoes rsueos
rsueso rssuoe rssueo rssoue rssoeu rsseou rsseuo rsosue rsoseu rsouse rsoues
rsoeus rsoesu rsesou rsesuo rseosu rseous rseuos rseuso reusso reusos reusso
reusos reuoss reuoss resuso resuos ressuo ressou resosu resous ressuo ressou
resuso resuos resous resosu reossu reosus reossu reosus reouss reouss orusse
oruses orusse oruses oruess oruess orsuse orsues orssue orsseu orsesu orseus
orssue orsseu orsuse orsues orseus orsesu oressu oresus oressu oresus oreuss
oreuss oursse ourses oursse ourses ouress ouress ousrse ousres oussre ousser
ousesr ousers oussre ousser ousrse ousres ousers ousesr ouessr ouesrs ouessr
ouesrs ouerss ouerss osurse osures osusre osuser osuesr osuers osruse osrues
osrsue osrseu osresu osreus ossrue ossreu ossure ossuer osseur osseru osersu
oserus osesru osesur oseusr oseurs osusre osuser osurse osures osuers osuesr
ossure ossuer ossrue ossreu osseru osseur osrsue osrseu osruse osrues osreus
osresu osesru osesur osersu oserus oseurs oseusr oeussr oeusrs oeussr oeusrs
oeurss oeurss oesusr oesurs oessur oessru oesrsu oesrus oessur oessru oesusr
oesurs oesrus oesrsu oerssu oersus oerssu oersus oeruss oeruss uorsse uorses
uorsse uorses uoress uoress uosrse uosres uossre uosser uosesr uosers uossre
uosser uosrse uosres uosers uosesr uoessr uoesrs uoessr uoesrs uoerss uoerss
urosse uroses urosse uroses uroess uroess ursose ursoes urssoe ursseo urseso
urseos urssoe ursseo ursose ursoes urseos urseso uresso uresos uresso uresos
ureoss ureoss usrose usroes usrsoe usrseo usreso usreos usorse usores usosre
usoser usoesr usoers ussore ussoer ussroe ussreo ussero usseor useosr useors
usesor usesro userso useros usrsoe usrseo usrose usroes usreos usreso ussroe
ussreo ussore ussoer usseor ussero usosre usoser usorse usores usoers usoesr
usesor usesro useosr useors useros userso uersso uersos uersso uersos ueross
ueross uesrso uesros uessro uessor uesosr uesors uessro uessor uesrso uesros
uesors uesosr ueossr ueosrs ueossr ueosrs ueorss ueorss sourse soures sousre
souser souesr souers soruse sorues sorsue sorseu soresu soreus sosrue sosreu
sosure sosuer soseur soseru soersu soerus soesru soesur soeusr soeurs suorse
suores suosre suoser suoesr suoers surose suroes sursoe surseo sureso sureos
susroe susreo susore susoer suseor susero suerso sueros suesro suesor sueosr
sueors sruose sruoes srusoe sruseo srueso srueos srouse sroues srosue sroseu
sroesu sroeus srsoue srsoeu srsuoe srsueo srseuo srseou sreosu sreous sresou
sresuo sreuso sreuos ssuroe ssureo ssuore ssuoer ssueor ssuero ssruoe ssrueo
ssroue ssroeu ssreou ssreuo ssorue ssoreu ssoure ssouer ssoeur ssoeru sserou
sseruo sseoru sseour sseuor sseuro seurso seuros seusro seusor seuosr seuors
seruso seruos sersuo sersou serosu serous sesruo sesrou sesuro sesuor sesour
sesoru seorsu seorus seosru seosur seousr seours sousre souser sourse soures
souers souesr sosure sosuer sosrue sosreu soseru soseur sorsue sorseu soruse
sorues soreus soresu soesru soesur soersu soerus soeurs soeusr suosre suoser
suorse suores suoers suoesr susore susoer susroe susreo susero suseor sursoe
surseo surose suroes sureos sureso suesro suesor suerso sueros sueors sueosr
ssuore ssuoer ssuroe ssureo ssuero ssueor ssoure ssouer ssorue ssoreu ssoeru
ssoeur ssroue ssroeu ssruoe ssrueo ssreuo ssreou sseoru sseour sserou sseruo
sseuro sseuor srusoe sruseo sruose sruoes srueos srueso srsuoe srsueo srsoue
srsoeu srseou srseuo srosue sroseu srouse sroues sroeus sroesu sresou sresuo
sreosu sreous sreuos sreuso seusro seusor seurso seuros seuors seuosr sesuro
sesuor sesruo sesrou sesoru sesour sersuo sersou seruso seruos serous serosu
seosru seosur seorsu seorus seours seousr eoussr eousrs eoussr eousrs eourss
eourss eosusr eosurs eossur eossru eosrsu eosrus eossur eossru eosusr eosurs
eosrus eosrsu eorssu eorsus eorssu eorsus eoruss eoruss euossr euosrs euossr
euosrs euorss euorss eusosr eusors eussor eussro eusrso eusros eussor eussro
eusosr eusors eusros eusrso eursso eursos eursso eursos euross euross esuosr
esuors esusor esusro esurso esuros esousr esours esosur esosru esorsu esorus
essour essoru essuor essuro essruo essrou esrosu esrous esrsou esrsuo esruso
esruos esusor esusro esuosr esuors esuros esurso essuor essuro essour essoru
essrou essruo esosur esosru esousr esours esorus esorsu esrsou esrsuo esrosu
esrous esruos esruso erusso erusos erusso erusos eruoss eruoss ersuso ersuos
erssuo erssou ersosu ersous erssuo erssou ersuso ersuos ersous ersosu erossu
erosus erossu erosus erouss erouss

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