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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: verdon
cipher variations:
wfsepo xgtfqp yhugrq zivhsr ajwits
bkxjut clykvu dmzlwv enamxw fobnyx
gpcozy hqdpaz ireqba jsfrcb ktgsdc
luhted mviufe nwjvgf oxkwhg pylxih
qzmyji ranzkj sboalk tcpbml udqcnm

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: verdon
Cipher: eviwlm

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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: verdon

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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: verdon
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: verdon
Cipher: ireqba

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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: verdon
Cipher: 155124414333

Extended Methods:
Method #1

Plaintext: verdon
method variations:

Method #2
Bifid cipher
The message is converted to its coordinates in the usual manner, but they are written vertically beneath:
v e r d o n 
1 5 2 4 4 3 
5 1 4 1 3 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: verdon
Cipher: vroedn

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Method #3

Plaintext: verdon
method variations:
zftqnc ftqncz tqnczf
qnczft nczftq czftqn

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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: verdon

all 720 cipher variations:
verdon verdno verodn verond vernod verndo vedron vedrno vedorn vedonr vednor
vednro veodrn veodnr veordn veornd veonrd veondr vendor vendro venodr venord
venrod venrdo vredon vredno vreodn vreond vrenod vrendo vrdeon vrdeno vrdoen
vrdone vrdnoe vrdneo vroden vrodne vroedn vroend vroned vronde vrndoe vrndeo
vrnode vrnoed vrneod vrnedo vdreon vdreno vdroen vdrone vdrnoe vdrneo vderon
vderno vdeorn vdeonr vdenor vdenro vdoern vdoenr vdoren vdorne vdonre vdoner
vdneor vdnero vdnoer vdnore vdnroe vdnreo vorden vordne voredn vorend vorned
vornde vodren vodrne vodern vodenr vodner vodnre voedrn voednr voerdn voernd
voenrd voendr vonder vondre vonedr vonerd vonred vonrde vnrdoe vnrdeo vnrode
vnroed vnreod vnredo vndroe vndreo vndore vndoer vndeor vndero vnodre vnoder
vnorde vnored vnoerd vnoedr vnedor vnedro vneodr vneord vnerod vnerdo evrdon
evrdno evrodn evrond evrnod evrndo evdron evdrno evdorn evdonr evdnor evdnro
evodrn evodnr evordn evornd evonrd evondr evndor evndro evnodr evnord evnrod
evnrdo ervdon ervdno ervodn ervond ervnod ervndo erdvon erdvno erdovn erdonv
erdnov erdnvo erodvn erodnv erovdn erovnd eronvd erondv erndov erndvo ernodv
ernovd ernvod ernvdo edrvon edrvno edrovn edronv edrnov edrnvo edvron edvrno
edvorn edvonr edvnor edvnro edovrn edovnr edorvn edornv edonrv edonvr ednvor
ednvro ednovr ednorv ednrov ednrvo eordvn eordnv eorvdn eorvnd eornvd eorndv
eodrvn eodrnv eodvrn eodvnr eodnvr eodnrv eovdrn eovdnr eovrdn eovrnd eovnrd
eovndr eondvr eondrv eonvdr eonvrd eonrvd eonrdv enrdov enrdvo enrodv enrovd
enrvod enrvdo endrov endrvo endorv endovr endvor endvro enodrv enodvr enordv
enorvd enovrd enovdr envdor envdro envodr envord envrod envrdo revdon revdno
revodn revond revnod revndo redvon redvno redovn redonv rednov rednvo reodvn
reodnv reovdn reovnd reonvd reondv rendov rendvo renodv renovd renvod renvdo
rvedon rvedno rveodn rveond rvenod rvendo rvdeon rvdeno rvdoen rvdone rvdnoe
rvdneo rvoden rvodne rvoedn rvoend rvoned rvonde rvndoe rvndeo rvnode rvnoed
rvneod rvnedo rdveon rdveno rdvoen rdvone rdvnoe rdvneo rdevon rdevno rdeovn
rdeonv rdenov rdenvo rdoevn rdoenv rdoven rdovne rdonve rdonev rdneov rdnevo
rdnoev rdnove rdnvoe rdnveo rovden rovdne rovedn rovend rovned rovnde rodven
rodvne rodevn rodenv rodnev rodnve roedvn roednv roevdn roevnd roenvd roendv
rondev rondve ronedv ronevd ronved ronvde rnvdoe rnvdeo rnvode rnvoed rnveod
rnvedo rndvoe rndveo rndove rndoev rndeov rndevo rnodve rnodev rnovde rnoved
rnoevd rnoedv rnedov rnedvo rneodv rneovd rnevod rnevdo dervon dervno derovn
deronv dernov dernvo devron devrno devorn devonr devnor devnro deovrn deovnr
deorvn deornv deonrv deonvr denvor denvro denovr denorv denrov denrvo drevon
drevno dreovn dreonv drenov drenvo drveon drveno drvoen drvone drvnoe drvneo
droven drovne droevn droenv dronev dronve drnvoe drnveo drnove drnoev drneov
drnevo dvreon dvreno dvroen dvrone dvrnoe dvrneo dveron dverno dveorn dveonr
dvenor dvenro dvoern dvoenr dvoren dvorne dvonre dvoner dvneor dvnero dvnoer
dvnore dvnroe dvnreo dorven dorvne dorevn dorenv dornev dornve dovren dovrne
dovern dovenr dovner dovnre doevrn doevnr doervn doernv doenrv doenvr donver
donvre donevr donerv donrev donrve dnrvoe dnrveo dnrove dnroev dnreov dnrevo
dnvroe dnvreo dnvore dnvoer dnveor dnvero dnovre dnover dnorve dnorev dnoerv
dnoevr dnevor dnevro dneovr dneorv dnerov dnervo oerdvn oerdnv oervdn oervnd
oernvd oerndv oedrvn oedrnv oedvrn oedvnr oednvr oednrv oevdrn oevdnr oevrdn
oevrnd oevnrd oevndr oendvr oendrv oenvdr oenvrd oenrvd oenrdv oredvn orednv
orevdn orevnd orenvd orendv ordevn ordenv ordven ordvne ordnve ordnev orvden
orvdne orvedn orvend orvned orvnde orndve orndev ornvde ornved ornevd ornedv
odrevn odrenv odrven odrvne odrnve odrnev odervn odernv odevrn odevnr odenvr
odenrv odvern odvenr odvren odvrne odvnre odvner odnevr odnerv odnver odnvre
odnrve odnrev ovrden ovrdne ovredn ovrend ovrned ovrnde ovdren ovdrne ovdern
ovdenr ovdner ovdnre ovedrn ovednr overdn overnd ovenrd ovendr ovnder ovndre
ovnedr ovnerd ovnred ovnrde onrdve onrdev onrvde onrved onrevd onredv ondrve
ondrev ondvre ondver ondevr onderv onvdre onvder onvrde onvred onverd onvedr
onedvr onedrv onevdr onevrd onervd onerdv nerdov nerdvo nerodv nerovd nervod
nervdo nedrov nedrvo nedorv nedovr nedvor nedvro neodrv neodvr neordv neorvd
neovrd neovdr nevdor nevdro nevodr nevord nevrod nevrdo nredov nredvo nreodv
nreovd nrevod nrevdo nrdeov nrdevo nrdoev nrdove nrdvoe nrdveo nrodev nrodve
nroedv nroevd nroved nrovde nrvdoe nrvdeo nrvode nrvoed nrveod nrvedo ndreov
ndrevo ndroev ndrove ndrvoe ndrveo nderov ndervo ndeorv ndeovr ndevor ndevro
ndoerv ndoevr ndorev ndorve ndovre ndover ndveor ndvero ndvoer ndvore ndvroe
ndvreo nordev nordve noredv norevd norved norvde nodrev nodrve noderv nodevr
nodver nodvre noedrv noedvr noerdv noervd noevrd noevdr novder novdre novedr
noverd novred novrde nvrdoe nvrdeo nvrode nvroed nvreod nvredo nvdroe nvdreo
nvdore nvdoer nvdeor nvdero nvodre nvoder nvorde nvored nvoerd nvoedr nvedor
nvedro nveodr nveord nverod nverdo

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