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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: thesun
cipher variations:
uiftvo vjguwp wkhvxq xliwyr ymjxzs
znkyat aolzbu bpmacv cqnbdw drocex
espdfy ftqegz gurfha hvsgib iwthjc
jxuikd kyvjle lzwkmf maxlng nbymoh
ocznpi pdaoqj qebprk rfcqsl sgdrtm

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: thesun
Cipher: gsvhfm

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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: thesun

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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: thesun
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: thesun
Cipher: gurfha

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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: thesun
Cipher: 443251345433

Extended Methods:
Method #1

Plaintext: thesun
method variations:

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

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Method #3

Plaintext: thesun
method variations:
owlyos wlyoso lyosow
yosowl osowly sowlyo

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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: thesun

all 720 cipher variations:
thesun thesnu theusn theuns thenus thensu thseun thsenu thsuen thsune thsnue
thsneu thusen thusne thuesn thuens thunes thunse thnsue thnseu thnuse thnues
thneus thnesu tehsun tehsnu tehusn tehuns tehnus tehnsu teshun teshnu tesuhn
tesunh tesnuh tesnhu teushn teusnh teuhsn teuhns teunhs teunsh tensuh tenshu
tenush tenuhs tenhus tenhsu tsehun tsehnu tseuhn tseunh tsenuh tsenhu tsheun
tshenu tshuen tshune tshnue tshneu tsuhen tsuhne tsuehn tsuenh tsuneh tsunhe
tsnhue tsnheu tsnuhe tsnueh tsneuh tsnehu tueshn tuesnh tuehsn tuehns tuenhs
tuensh tusehn tusenh tushen tushne tusnhe tusneh tuhsen tuhsne tuhesn tuhens
tuhnes tuhnse tunshe tunseh tunhse tunhes tunehs tunesh tnesuh tneshu tneush
tneuhs tnehus tnehsu tnseuh tnsehu tnsueh tnsuhe tnshue tnsheu tnuseh tnushe
tnuesh tnuehs tnuhes tnuhse tnhsue tnhseu tnhuse tnhues tnheus tnhesu htesun
htesnu hteusn hteuns htenus htensu htseun htsenu htsuen htsune htsnue htsneu
htusen htusne htuesn htuens htunes htunse htnsue htnseu htnuse htnues htneus
htnesu hetsun hetsnu hetusn hetuns hetnus hetnsu hestun hestnu hesutn hesunt
hesnut hesntu heustn heusnt heutsn heutns heunts heunst hensut henstu henust
henuts hentus hentsu hsetun hsetnu hseutn hseunt hsenut hsentu hsteun hstenu
hstuen hstune hstnue hstneu hsuten hsutne hsuetn hsuent hsunet hsunte hsntue
hsnteu hsnute hsnuet hsneut hsnetu huestn huesnt huetsn huetns huents huenst
husetn husent husten hustne husnte husnet hutsen hutsne hutesn hutens hutnes
hutnse hunste hunset huntse huntes hunets hunest hnesut hnestu hneust hneuts
hnetus hnetsu hnseut hnsetu hnsuet hnsute hnstue hnsteu hnuset hnuste hnuest
hnuets hnutes hnutse hntsue hntseu hntuse hntues hnteus hntesu ehtsun ehtsnu
ehtusn ehtuns ehtnus ehtnsu ehstun ehstnu ehsutn ehsunt ehsnut ehsntu ehustn
ehusnt ehutsn ehutns ehunts ehunst ehnsut ehnstu ehnust ehnuts ehntus ehntsu
ethsun ethsnu ethusn ethuns ethnus ethnsu etshun etshnu etsuhn etsunh etsnuh
etsnhu etushn etusnh etuhsn etuhns etunhs etunsh etnsuh etnshu etnush etnuhs
etnhus etnhsu esthun esthnu estuhn estunh estnuh estnhu eshtun eshtnu eshutn
eshunt eshnut eshntu esuhtn esuhnt esuthn esutnh esunth esunht esnhut esnhtu
esnuht esnuth esntuh esnthu eutshn eutsnh euthsn euthns eutnhs eutnsh eusthn
eustnh eushtn eushnt eusnht eusnth euhstn euhsnt euhtsn euhtns euhnts euhnst
eunsht eunsth eunhst eunhts eunths euntsh entsuh entshu entush entuhs enthus
enthsu enstuh ensthu ensuth ensuht enshut enshtu enusth enusht enutsh enuths
enuhts enuhst enhsut enhstu enhust enhuts enhtus enhtsu shetun shetnu sheutn
sheunt shenut shentu shteun shtenu shtuen shtune shtnue shtneu shuten shutne
shuetn shuent shunet shunte shntue shnteu shnute shnuet shneut shnetu sehtun
sehtnu sehutn sehunt sehnut sehntu sethun sethnu setuhn setunh setnuh setnhu
seuthn seutnh seuhtn seuhnt seunht seunth sentuh senthu senuth senuht senhut
senhtu stehun stehnu steuhn steunh stenuh stenhu stheun sthenu sthuen sthune
sthnue sthneu stuhen stuhne stuehn stuenh stuneh stunhe stnhue stnheu stnuhe
stnueh stneuh stnehu suethn suetnh suehtn suehnt suenht suenth sutehn sutenh
suthen suthne sutnhe sutneh suhten suhtne suhetn suhent suhnet suhnte sunthe
sunteh sunhte sunhet suneht suneth snetuh snethu sneuth sneuht snehut snehtu
snteuh sntehu sntueh sntuhe snthue sntheu snuteh snuthe snueth snueht snuhet
snuhte snhtue snhteu snhute snhuet snheut snhetu uhestn uhesnt uhetsn uhetns
uhents uhenst uhsetn uhsent uhsten uhstne uhsnte uhsnet uhtsen uhtsne uhtesn
uhtens uhtnes uhtnse uhnste uhnset uhntse uhntes uhnets uhnest uehstn uehsnt
uehtsn uehtns uehnts uehnst ueshtn ueshnt uesthn uestnh uesnth uesnht uetshn
uetsnh uethsn uethns uetnhs uetnsh uensth uensht uentsh uenths uenhts uenhst
usehtn usehnt usethn usetnh usenth usenht ushetn ushent ushten ushtne ushnte
ushnet usthen usthne ustehn ustenh ustneh ustnhe usnhte usnhet usnthe usnteh
usneth usneht uteshn utesnh utehsn utehns utenhs utensh utsehn utsenh utshen
utshne utsnhe utsneh uthsen uthsne uthesn uthens uthnes uthnse utnshe utnseh
utnhse utnhes utnehs utnesh unesth unesht unetsh uneths unehts unehst unseth
unseht unsteh unsthe unshte unshet untseh untshe untesh untehs unthes unthse
unhste unhset unhtse unhtes unhets unhest nhesut nhestu nheust nheuts nhetus
nhetsu nhseut nhsetu nhsuet nhsute nhstue nhsteu nhuset nhuste nhuest nhuets
nhutes nhutse nhtsue nhtseu nhtuse nhtues nhteus nhtesu nehsut nehstu nehust
nehuts nehtus nehtsu neshut neshtu nesuht nesuth nestuh nesthu neusht neusth
neuhst neuhts neuths neutsh netsuh netshu netush netuhs nethus nethsu nsehut
nsehtu nseuht nseuth nsetuh nsethu nsheut nshetu nshuet nshute nshtue nshteu
nsuhet nsuhte nsueht nsueth nsuteh nsuthe nsthue nstheu nstuhe nstueh nsteuh
nstehu nuesht nuesth nuehst nuehts nueths nuetsh nuseht nuseth nushet nushte
nusthe nusteh nuhset nuhste nuhest nuhets nuhtes nuhtse nutshe nutseh nuthse
nuthes nutehs nutesh ntesuh nteshu nteush nteuhs ntehus ntehsu ntseuh ntsehu
ntsueh ntsuhe ntshue ntsheu ntuseh ntushe ntuesh ntuehs ntuhes ntuhse nthsue
nthseu nthuse nthues ntheus nthesu

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