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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: wakeup
cipher variations:
xblfvq ycmgwr zdnhxs aeoiyt bfpjzu
cgqkav dhrlbw eismcx fjtndy gkuoez
hlvpfa imwqgb jnxrhc koysid lpztje
mqaukf nrbvlg oscwmh ptdxni queyoj
rvfzpk swgaql txhbrm uyicsn vzjdto

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: wakeup
Cipher: dzpvfk

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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: wakeup

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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: wakeup
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: wakeup
Cipher: jnxrhc

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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: wakeup
Cipher: 251152515453

Extended Methods:
Method #1

Plaintext: wakeup
method variations:

Method #2
Bifid cipher
The message is converted to its coordinates in the usual manner, but they are written vertically beneath:
w a k e u p 
2 1 5 5 5 5 
5 1 2 1 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: wakeup
Cipher: bzzebo

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Method #3

Plaintext: wakeup
method variations:
evwvyh vwvyhe wvyhev
vyhevw yhevwv hevwvy

Read more ...[RUS] , [EN]


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: wakeup

all 720 cipher variations:
wakeup wakepu wakuep wakupe wakpue wakpeu waekup waekpu waeukp waeupk waepuk
waepku wauekp wauepk waukep waukpe waupke waupek wapeuk wapeku wapuek wapuke
wapkue wapkeu wkaeup wkaepu wkauep wkaupe wkapue wkapeu wkeaup wkeapu wkeuap
wkeupa wkepua wkepau wkueap wkuepa wkuaep wkuape wkupae wkupea wkpeua wkpeau
wkpuea wkpuae wkpaue wkpaeu wekaup wekapu wekuap wekupa wekpua wekpau weakup
weakpu weaukp weaupk weapuk weapku weuakp weuapk weukap weukpa weupka weupak
wepauk wepaku wepuak wepuka wepkua wepkau wukeap wukepa wukaep wukape wukpae
wukpea wuekap wuekpa wueakp wueapk wuepak wuepka wuaekp wuaepk wuakep wuakpe
wuapke wuapek wupeak wupeka wupaek wupake wupkae wupkea wpkeua wpkeau wpkuea
wpkuae wpkaue wpkaeu wpekua wpekau wpeuka wpeuak wpeauk wpeaku wpueka wpueak
wpukea wpukae wpuake wpuaek wpaeuk wpaeku wpauek wpauke wpakue wpakeu awkeup
awkepu awkuep awkupe awkpue awkpeu awekup awekpu aweukp aweupk awepuk awepku
awuekp awuepk awukep awukpe awupke awupek awpeuk awpeku awpuek awpuke awpkue
awpkeu akweup akwepu akwuep akwupe akwpue akwpeu akewup akewpu akeuwp akeupw
akepuw akepwu akuewp akuepw akuwep akuwpe akupwe akupew akpeuw akpewu akpuew
akpuwe akpwue akpweu aekwup aekwpu aekuwp aekupw aekpuw aekpwu aewkup aewkpu
aewukp aewupk aewpuk aewpku aeuwkp aeuwpk aeukwp aeukpw aeupkw aeupwk aepwuk
aepwku aepuwk aepukw aepkuw aepkwu aukewp aukepw aukwep aukwpe aukpwe aukpew
auekwp auekpw auewkp auewpk auepwk auepkw auwekp auwepk auwkep auwkpe auwpke
auwpek aupewk aupekw aupwek aupwke aupkwe aupkew apkeuw apkewu apkuew apkuwe
apkwue apkweu apekuw apekwu apeukw apeuwk apewuk apewku apuekw apuewk apukew
apukwe apuwke apuwek apweuk apweku apwuek apwuke apwkue apwkeu kaweup kawepu
kawuep kawupe kawpue kawpeu kaewup kaewpu kaeuwp kaeupw kaepuw kaepwu kauewp
kauepw kauwep kauwpe kaupwe kaupew kapeuw kapewu kapuew kapuwe kapwue kapweu
kwaeup kwaepu kwauep kwaupe kwapue kwapeu kweaup kweapu kweuap kweupa kwepua
kwepau kwueap kwuepa kwuaep kwuape kwupae kwupea kwpeua kwpeau kwpuea kwpuae
kwpaue kwpaeu kewaup kewapu kewuap kewupa kewpua kewpau keawup keawpu keauwp
keaupw keapuw keapwu keuawp keuapw keuwap keuwpa keupwa keupaw kepauw kepawu
kepuaw kepuwa kepwua kepwau kuweap kuwepa kuwaep kuwape kuwpae kuwpea kuewap
kuewpa kueawp kueapw kuepaw kuepwa kuaewp kuaepw kuawep kuawpe kuapwe kuapew
kupeaw kupewa kupaew kupawe kupwae kupwea kpweua kpweau kpwuea kpwuae kpwaue
kpwaeu kpewua kpewau kpeuwa kpeuaw kpeauw kpeawu kpuewa kpueaw kpuwea kpuwae
kpuawe kpuaew kpaeuw kpaewu kpauew kpauwe kpawue kpaweu eakwup eakwpu eakuwp
eakupw eakpuw eakpwu eawkup eawkpu eawukp eawupk eawpuk eawpku eauwkp eauwpk
eaukwp eaukpw eaupkw eaupwk eapwuk eapwku eapuwk eapukw eapkuw eapkwu ekawup
ekawpu ekauwp ekaupw ekapuw ekapwu ekwaup ekwapu ekwuap ekwupa ekwpua ekwpau
ekuwap ekuwpa ekuawp ekuapw ekupaw ekupwa ekpwua ekpwau ekpuwa ekpuaw ekpauw
ekpawu ewkaup ewkapu ewkuap ewkupa ewkpua ewkpau ewakup ewakpu ewaukp ewaupk
ewapuk ewapku ewuakp ewuapk ewukap ewukpa ewupka ewupak ewpauk ewpaku ewpuak
ewpuka ewpkua ewpkau eukwap eukwpa eukawp eukapw eukpaw eukpwa euwkap euwkpa
euwakp euwapk euwpak euwpka euawkp euawpk euakwp euakpw euapkw euapwk eupwak
eupwka eupawk eupakw eupkaw eupkwa epkwua epkwau epkuwa epkuaw epkauw epkawu
epwkua epwkau epwuka epwuak epwauk epwaku epuwka epuwak epukwa epukaw epuakw
epuawk epawuk epawku epauwk epaukw epakuw epakwu uakewp uakepw uakwep uakwpe
uakpwe uakpew uaekwp uaekpw uaewkp uaewpk uaepwk uaepkw uawekp uawepk uawkep
uawkpe uawpke uawpek uapewk uapekw uapwek uapwke uapkwe uapkew ukaewp ukaepw
ukawep ukawpe ukapwe ukapew ukeawp ukeapw ukewap ukewpa ukepwa ukepaw ukweap
ukwepa ukwaep ukwape ukwpae ukwpea ukpewa ukpeaw ukpwea ukpwae ukpawe ukpaew
uekawp uekapw uekwap uekwpa uekpwa uekpaw ueakwp ueakpw ueawkp ueawpk ueapwk
ueapkw uewakp uewapk uewkap uewkpa uewpka uewpak uepawk uepakw uepwak uepwka
uepkwa uepkaw uwkeap uwkepa uwkaep uwkape uwkpae uwkpea uwekap uwekpa uweakp
uweapk uwepak uwepka uwaekp uwaepk uwakep uwakpe uwapke uwapek uwpeak uwpeka
uwpaek uwpake uwpkae uwpkea upkewa upkeaw upkwea upkwae upkawe upkaew upekwa
upekaw upewka upewak upeawk upeakw upweka upweak upwkea upwkae upwake upwaek
upaewk upaekw upawek upawke upakwe upakew pakeuw pakewu pakuew pakuwe pakwue
pakweu paekuw paekwu paeukw paeuwk paewuk paewku pauekw pauewk paukew paukwe
pauwke pauwek paweuk paweku pawuek pawuke pawkue pawkeu pkaeuw pkaewu pkauew
pkauwe pkawue pkaweu pkeauw pkeawu pkeuaw pkeuwa pkewua pkewau pkueaw pkuewa
pkuaew pkuawe pkuwae pkuwea pkweua pkweau pkwuea pkwuae pkwaue pkwaeu pekauw
pekawu pekuaw pekuwa pekwua pekwau peakuw peakwu peaukw peauwk peawuk peawku
peuakw peuawk peukaw peukwa peuwka peuwak pewauk pewaku pewuak pewuka pewkua
pewkau pukeaw pukewa pukaew pukawe pukwae pukwea puekaw puekwa pueakw pueawk
puewak puewka puaekw puaewk puakew puakwe puawke puawek puweak puweka puwaek
puwake puwkae puwkea pwkeua pwkeau pwkuea pwkuae pwkaue pwkaeu pwekua pwekau
pweuka pweuak pweauk pweaku pwueka pwueak pwukea pwukae pwuake pwuaek pwaeuk
pwaeku pwauek pwauke pwakue pwakeu

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History of cryptography
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