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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: sancte
cipher variations:
tboduf ucpevg vdqfwh wergxi xfshyj
ygtizk zhujal aivkbm bjwlcn ckxmdo
dlynep emzofq fnapgr gobqhs hpcrit
iqdsju jretkv ksfulw ltgvmx muhwny
nvixoz owjypa pxkzqb qylarc rzmbsd

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: sancte
Cipher: hzmxgv

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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: sancte

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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: sancte
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: sancte
Cipher: fnapgr

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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: sancte
Cipher: 341133314451

Extended Methods:
Method #1

Plaintext: sancte
method variations:

Method #2
Bifid cipher
The message is converted to its coordinates in the usual manner, but they are written vertically beneath:
s a n c t e 
3 1 3 3 4 5 
4 1 3 1 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: sancte
Cipher: cnydcd

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Method #3

Plaintext: sancte
method variations:
dlnqyl lnqyld nqyldl
qyldln yldlnq ldlnqy

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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: sancte

all 720 cipher variations:
sancte sancet santce santec sanetc sanect sacnte sacnet sactne sacten sacetn
sacent satcne satcen satnce satnec satenc satecn saectn saecnt saetcn saetnc
saentc saenct snacte snacet snatce snatec snaetc snaect sncate sncaet snctae
snctea snceta snceat sntcae sntcea sntace sntaec snteac snteca snecta snecat
snetca snetac sneatc sneact scnate scnaet scntae scntea scneta scneat scante
scanet scatne scaten scaetn scaent sctane sctaen sctnae sctnea sctena sctean
sceatn sceant scetan scetna scenta scenat stncae stncea stnace stnaec stneac
stneca stcnae stcnea stcane stcaen stcean stcena stacne stacen stance stanec
staenc staecn stecan stecna steacn steanc stenac stenca sencta sencat sentca
sentac senatc senact secnta secnat sectna sectan secatn secant setcna setcan
setnca setnac setanc setacn seactn seacnt seatcn seatnc seantc seanct asncte
asncet asntce asntec asnetc asnect ascnte ascnet asctne ascten ascetn ascent
astcne astcen astnce astnec astenc astecn asectn asecnt asetcn asetnc asentc
asenct anscte anscet anstce anstec ansetc ansect ancste ancset anctse anctes
ancets ancest antcse antces antsce antsec antesc antecs anects anecst anetcs
anetsc anestc anesct acnste acnset acntse acntes acnets acnest acsnte acsnet
acstne acsten acsetn acsent actsne actsen actnse actnes actens actesn acestn
acesnt acetsn acetns acents acenst atncse atnces atnsce atnsec atnesc atnecs
atcnse atcnes atcsne atcsen atcesn atcens atscne atscen atsnce atsnec atsenc
atsecn atecsn atecns atescn atesnc atensc atencs aencts aencst aentcs aentsc
aenstc aensct aecnts aecnst aectns aectsn aecstn aecsnt aetcns aetcsn aetncs
aetnsc aetsnc aetscn aesctn aescnt aestcn aestnc aesntc aesnct nascte nascet
nastce nastec nasetc nasect nacste nacset nactse nactes nacets nacest natcse
natces natsce natsec natesc natecs naects naecst naetcs naetsc naestc naesct
nsacte nsacet nsatce nsatec nsaetc nsaect nscate nscaet nsctae nsctea nsceta
nsceat nstcae nstcea nstace nstaec nsteac nsteca nsecta nsecat nsetca nsetac
nseatc nseact ncsate ncsaet ncstae ncstea ncseta ncseat ncaste ncaset ncatse
ncates ncaets ncaest nctase nctaes nctsae nctsea nctesa ncteas nceats nceast
ncetas ncetsa ncesta ncesat ntscae ntscea ntsace ntsaec ntseac ntseca ntcsae
ntcsea ntcase ntcaes ntceas ntcesa ntacse ntaces ntasce ntasec ntaesc ntaecs
ntecas ntecsa nteacs nteasc ntesac ntesca nescta nescat nestca nestac nesatc
nesact necsta necsat nectsa nectas necats necast netcsa netcas netsca netsac
netasc netacs neacts neacst neatcs neatsc neastc neasct canste canset cantse
cantes canets canest casnte casnet castne casten casetn casent catsne catsen
catnse catnes catens catesn caestn caesnt caetsn caetns caents caenst cnaste
cnaset cnatse cnates cnaets cnaest cnsate cnsaet cnstae cnstea cnseta cnseat
cntsae cntsea cntase cntaes cnteas cntesa cnesta cnesat cnetsa cnetas cneats
cneast csnate csnaet csntae csntea csneta csneat csante csanet csatne csaten
csaetn csaent cstane cstaen cstnae cstnea cstena cstean cseatn cseant csetan
csetna csenta csenat ctnsae ctnsea ctnase ctnaes ctneas ctnesa ctsnae ctsnea
ctsane ctsaen ctsean ctsena ctasne ctasen ctanse ctanes ctaens ctaesn ctesan
ctesna cteasn cteans ctenas ctensa censta censat centsa centas cenats cenast
cesnta cesnat cestna cestan cesatn cesant cetsna cetsan cetnsa cetnas cetans
cetasn ceastn ceasnt ceatsn ceatns ceants ceanst tancse tances tansce tansec
tanesc tanecs tacnse tacnes tacsne tacsen tacesn tacens tascne tascen tasnce
tasnec tasenc tasecn taecsn taecns taescn taesnc taensc taencs tnacse tnaces
tnasce tnasec tnaesc tnaecs tncase tncaes tncsae tncsea tncesa tnceas tnscae
tnscea tnsace tnsaec tnseac tnseca tnecsa tnecas tnesca tnesac tneasc tneacs
tcnase tcnaes tcnsae tcnsea tcnesa tcneas tcanse tcanes tcasne tcasen tcaesn
tcaens tcsane tcsaen tcsnae tcsnea tcsena tcsean tceasn tceans tcesan tcesna
tcensa tcenas tsncae tsncea tsnace tsnaec tsneac tsneca tscnae tscnea tscane
tscaen tscean tscena tsacne tsacen tsance tsanec tsaenc tsaecn tsecan tsecna
tseacn tseanc tsenac tsenca tencsa tencas tensca tensac tenasc tenacs tecnsa
tecnas tecsna tecsan tecasn tecans tescna tescan tesnca tesnac tesanc tesacn
teacsn teacns teascn teasnc teansc teancs eancts eancst eantcs eantsc eanstc
eansct eacnts eacnst eactns eactsn eacstn eacsnt eatcns eatcsn eatncs eatnsc
eatsnc eatscn easctn eascnt eastcn eastnc easntc easnct enacts enacst enatcs
enatsc enastc enasct encats encast enctas enctsa encsta encsat entcas entcsa
entacs entasc entsac entsca enscta enscat enstca enstac ensatc ensact ecnats
ecnast ecntas ecntsa ecnsta ecnsat ecants ecanst ecatns ecatsn ecastn ecasnt
ectans ectasn ectnas ectnsa ectsna ectsan ecsatn ecsant ecstan ecstna ecsnta
ecsnat etncas etncsa etnacs etnasc etnsac etnsca etcnas etcnsa etcans etcasn
etcsan etcsna etacns etacsn etancs etansc etasnc etascn etscan etscna etsacn
etsanc etsnac etsnca esncta esncat esntca esntac esnatc esnact escnta escnat
esctna esctan escatn escant estcna estcan estnca estnac estanc estacn esactn
esacnt esatcn esatnc esantc esanct

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