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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: judges
cipher variations:
kvehft lwfigu mxgjhv nyhkiw oziljx
pajmky qbknlz rcloma sdmpnb tenqoc
uforpd vgpsqe whqtrf xirusg yjsvth
zktwui aluxvj bmvywk cnwzxl doxaym
epybzn fqzcao gradbp hsbecq itcfdr

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: judges
Cipher: qfwtvh

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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: judges

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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: judges
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: judges
Cipher: whqtrf

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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: judges
Cipher: 425441225134

Extended Methods:
Method #1

Plaintext: judges
method variations:

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

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Method #3

Plaintext: judges
method variations:
wtfwlt tfwltw fwltwt
wltwtf ltwtfw twtfwl

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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: judges

all 720 cipher variations:
judges judgse judegs judesg judseg judsge jugdes jugdse jugeds jugesd jugsed
jugsde juegds juegsd juedgs juedsg juesdg juesgd jusged jusgde jusegd jusedg
jusdeg jusdge jduges jdugse jduegs jduesg jduseg jdusge jdgues jdguse jdgeus
jdgesu jdgseu jdgsue jdegus jdegsu jdeugs jdeusg jdesug jdesgu jdsgeu jdsgue
jdsegu jdseug jdsueg jdsuge jgdues jgduse jgdeus jgdesu jgdseu jgdsue jgudes
jgudse jgueds jguesd jgused jgusde jgeuds jgeusd jgedus jgedsu jgesdu jgesud
jgsued jgsude jgseud jgsedu jgsdeu jgsdue jedgus jedgsu jedugs jedusg jedsug
jedsgu jegdus jegdsu jeguds jegusd jegsud jegsdu jeugds jeugsd jeudgs jeudsg
jeusdg jeusgd jesgud jesgdu jesugd jesudg jesdug jesdgu jsdgeu jsdgue jsdegu
jsdeug jsdueg jsduge jsgdeu jsgdue jsgedu jsgeud jsgued jsgude jsegdu jsegud
jsedgu jsedug jseudg jseugd jsuged jsugde jsuegd jsuedg jsudeg jsudge ujdges
ujdgse ujdegs ujdesg ujdseg ujdsge ujgdes ujgdse ujgeds ujgesd ujgsed ujgsde
ujegds ujegsd ujedgs ujedsg ujesdg ujesgd ujsged ujsgde ujsegd ujsedg ujsdeg
ujsdge udjges udjgse udjegs udjesg udjseg udjsge udgjes udgjse udgejs udgesj
udgsej udgsje udegjs udegsj udejgs udejsg udesjg udesgj udsgej udsgje udsegj
udsejg udsjeg udsjge ugdjes ugdjse ugdejs ugdesj ugdsej ugdsje ugjdes ugjdse
ugjeds ugjesd ugjsed ugjsde ugejds ugejsd ugedjs ugedsj ugesdj ugesjd ugsjed
ugsjde ugsejd ugsedj ugsdej ugsdje uedgjs uedgsj uedjgs uedjsg uedsjg uedsgj
uegdjs uegdsj uegjds uegjsd uegsjd uegsdj uejgds uejgsd uejdgs uejdsg uejsdg
uejsgd uesgjd uesgdj uesjgd uesjdg uesdjg uesdgj usdgej usdgje usdegj usdejg
usdjeg usdjge usgdej usgdje usgedj usgejd usgjed usgjde usegdj usegjd usedgj
usedjg usejdg usejgd usjged usjgde usjegd usjedg usjdeg usjdge dujges dujgse
dujegs dujesg dujseg dujsge dugjes dugjse dugejs dugesj dugsej dugsje duegjs
duegsj duejgs duejsg duesjg duesgj dusgej dusgje dusegj dusejg dusjeg dusjge
djuges djugse djuegs djuesg djuseg djusge djgues djguse djgeus djgesu djgseu
djgsue djegus djegsu djeugs djeusg djesug djesgu djsgeu djsgue djsegu djseug
djsueg djsuge dgjues dgjuse dgjeus dgjesu dgjseu dgjsue dgujes dgujse dguejs
dguesj dgusej dgusje dgeujs dgeusj dgejus dgejsu dgesju dgesuj dgsuej dgsuje
dgseuj dgseju dgsjeu dgsjue dejgus dejgsu dejugs dejusg dejsug dejsgu degjus
degjsu degujs degusj degsuj degsju deugjs deugsj deujgs deujsg deusjg deusgj
desguj desgju desugj desujg desjug desjgu dsjgeu dsjgue dsjegu dsjeug dsjueg
dsjuge dsgjeu dsgjue dsgeju dsgeuj dsguej dsguje dsegju dseguj dsejgu dsejug
dseujg dseugj dsugej dsugje dsuegj dsuejg dsujeg dsujge gudjes gudjse gudejs
gudesj gudsej gudsje gujdes gujdse gujeds gujesd gujsed gujsde guejds guejsd
guedjs guedsj guesdj guesjd gusjed gusjde gusejd gusedj gusdej gusdje gdujes
gdujse gduejs gduesj gdusej gdusje gdjues gdjuse gdjeus gdjesu gdjseu gdjsue
gdejus gdejsu gdeujs gdeusj gdesuj gdesju gdsjeu gdsjue gdseju gdseuj gdsuej
gdsuje gjdues gjduse gjdeus gjdesu gjdseu gjdsue gjudes gjudse gjueds gjuesd
gjused gjusde gjeuds gjeusd gjedus gjedsu gjesdu gjesud gjsued gjsude gjseud
gjsedu gjsdeu gjsdue gedjus gedjsu gedujs gedusj gedsuj gedsju gejdus gejdsu
gejuds gejusd gejsud gejsdu geujds geujsd geudjs geudsj geusdj geusjd gesjud
gesjdu gesujd gesudj gesduj gesdju gsdjeu gsdjue gsdeju gsdeuj gsduej gsduje
gsjdeu gsjdue gsjedu gsjeud gsjued gsjude gsejdu gsejud gsedju gseduj gseudj
gseujd gsujed gsujde gsuejd gsuedj gsudej gsudje eudgjs eudgsj eudjgs eudjsg
eudsjg eudsgj eugdjs eugdsj eugjds eugjsd eugsjd eugsdj eujgds eujgsd eujdgs
eujdsg eujsdg eujsgd eusgjd eusgdj eusjgd eusjdg eusdjg eusdgj edugjs edugsj
edujgs edujsg edusjg edusgj edgujs edgusj edgjus edgjsu edgsju edgsuj edjgus
edjgsu edjugs edjusg edjsug edjsgu edsgju edsguj edsjgu edsjug edsujg edsugj
egdujs egdusj egdjus egdjsu egdsju egdsuj egudjs egudsj egujds egujsd egusjd
egusdj egjuds egjusd egjdus egjdsu egjsdu egjsud egsujd egsudj egsjud egsjdu
egsdju egsduj ejdgus ejdgsu ejdugs ejdusg ejdsug ejdsgu ejgdus ejgdsu ejguds
ejgusd ejgsud ejgsdu ejugds ejugsd ejudgs ejudsg ejusdg ejusgd ejsgud ejsgdu
ejsugd ejsudg ejsdug ejsdgu esdgju esdguj esdjgu esdjug esdujg esdugj esgdju
esgduj esgjdu esgjud esgujd esgudj esjgdu esjgud esjdgu esjdug esjudg esjugd
esugjd esugdj esujgd esujdg esudjg esudgj sudgej sudgje sudegj sudejg sudjeg
sudjge sugdej sugdje sugedj sugejd sugjed sugjde suegdj suegjd suedgj suedjg
suejdg suejgd sujged sujgde sujegd sujedg sujdeg sujdge sdugej sdugje sduegj
sduejg sdujeg sdujge sdguej sdguje sdgeuj sdgeju sdgjeu sdgjue sdeguj sdegju
sdeugj sdeujg sdejug sdejgu sdjgeu sdjgue sdjegu sdjeug sdjueg sdjuge sgduej
sgduje sgdeuj sgdeju sgdjeu sgdjue sgudej sgudje sguedj sguejd sgujed sgujde
sgeudj sgeujd sgeduj sgedju sgejdu sgejud sgjued sgjude sgjeud sgjedu sgjdeu
sgjdue sedguj sedgju sedugj sedujg sedjug sedjgu segduj segdju segudj segujd
segjud segjdu seugdj seugjd seudgj seudjg seujdg seujgd sejgud sejgdu sejugd
sejudg sejdug sejdgu sjdgeu sjdgue sjdegu sjdeug sjdueg sjduge sjgdeu sjgdue
sjgedu sjgeud sjgued sjgude sjegdu sjegud sjedgu sjedug sjeudg sjeugd sjuged
sjugde sjuegd sjuedg sjudeg sjudge

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