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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: flater
cipher variations:
gmbufs hncvgt iodwhu jpexiv kqfyjw
lrgzkx mshaly ntibmz oujcna pvkdob
qwlepc rxmfqd syngre tzohsf uapitg
vbqjuh wcrkvi xdslwj yetmxk zfunyl
agvozm bhwpan cixqbo djyrcp ekzsdq

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: flater
Cipher: uozgvi

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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: flater

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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: flater
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: flater
Cipher: syngre

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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: flater
Cipher: 121311445124

Extended Methods:
Method #1

Plaintext: flater
method variations:

Method #2
Bifid cipher
The message is converted to its coordinates in the usual manner, but they are written vertically beneath:
f l a t e r 
1 1 1 4 5 2 
2 3 1 4 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: flater
Cipher: aqkmqq

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Method #3

Plaintext: flater
method variations:
bcqyfd cqyfdb qyfdbc
yfdbcq fdbcqy dbcqyf

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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: flater

all 720 cipher variations:
flater flatre flaetr flaert flaret flarte fltaer fltare fltear fltera fltrea
fltrae fletar fletra fleatr fleart flerat flerta flrtea flrtae flreta flreat
flraet flrate falter faltre faletr falert falret falrte fatler fatlre fatelr
faterl fatrel fatrle faetlr faetrl faeltr faelrt faerlt faertl fartel fartle
faretl farelt farlet farlte ftaler ftalre ftaelr ftaerl ftarel ftarle ftlaer
ftlare ftlear ftlera ftlrea ftlrae ftelar ftelra ftealr ftearl fteral fterla
ftrlea ftrlae ftrela ftreal ftrael ftrale featlr featrl fealtr fealrt fearlt
feartl fetalr fetarl fetlar fetlra fetrla fetral feltar feltra felatr felart
felrat felrta fertla fertal ferlta ferlat feralt feratl fratel fratle fraetl
fraelt fralet fralte frtael frtale frteal frtela frtlea frtlae fretal fretla
freatl frealt frelat frelta frltea frltae frleta frleat frlaet frlate lfater
lfatre lfaetr lfaert lfaret lfarte lftaer lftare lftear lftera lftrea lftrae
lfetar lfetra lfeatr lfeart lferat lferta lfrtea lfrtae lfreta lfreat lfraet
lfrate lafter laftre lafetr lafert lafret lafrte latfer latfre latefr laterf
latref latrfe laetfr laetrf laeftr laefrt laerft laertf lartef lartfe laretf
lareft larfet larfte ltafer ltafre ltaefr ltaerf ltaref ltarfe ltfaer ltfare
ltfear ltfera ltfrea ltfrae ltefar ltefra lteafr ltearf lteraf lterfa ltrfea
ltrfae ltrefa ltreaf ltraef ltrafe leatfr leatrf leaftr leafrt learft leartf
letafr letarf letfar letfra letrfa letraf leftar leftra lefatr lefart lefrat
lefrta lertfa lertaf lerfta lerfat leraft leratf lratef lratfe lraetf lraeft
lrafet lrafte lrtaef lrtafe lrteaf lrtefa lrtfea lrtfae lretaf lretfa lreatf
lreaft lrefat lrefta lrftea lrftae lrfeta lrfeat lrfaet lrfate alfter alftre
alfetr alfert alfret alfrte altfer altfre altefr alterf altref altrfe aletfr
aletrf aleftr alefrt alerft alertf alrtef alrtfe alretf alreft alrfet alrfte
aflter afltre afletr aflert aflret aflrte aftler aftlre aftelr afterl aftrel
aftrle afetlr afetrl afeltr afelrt aferlt afertl afrtel afrtle afretl afrelt
afrlet afrlte atfler atflre atfelr atferl atfrel atfrle atlfer atlfre atlefr
atlerf atlref atlrfe atelfr atelrf ateflr atefrl aterfl aterlf atrlef atrlfe
atrelf atrefl atrfel atrfle aeftlr aeftrl aefltr aeflrt aefrlt aefrtl aetflr
aetfrl aetlfr aetlrf aetrlf aetrfl aeltfr aeltrf aelftr aelfrt aelrft aelrtf
aertlf aertfl aerltf aerlft aerflt aerftl arftel arftle arfetl arfelt arflet
arflte artfel artfle artefl artelf artlef artlfe aretfl aretlf areftl areflt
arelft areltf arltef arltfe arletf arleft arlfet arlfte tlafer tlafre tlaefr
tlaerf tlaref tlarfe tlfaer tlfare tlfear tlfera tlfrea tlfrae tlefar tlefra
tleafr tlearf tleraf tlerfa tlrfea tlrfae tlrefa tlreaf tlraef tlrafe talfer
talfre talefr talerf talref talrfe tafler taflre tafelr taferl tafrel tafrle
taeflr taefrl taelfr taelrf taerlf taerfl tarfel tarfle tarefl tarelf tarlef
tarlfe tfaler tfalre tfaelr tfaerl tfarel tfarle tflaer tflare tflear tflera
tflrea tflrae tfelar tfelra tfealr tfearl tferal tferla tfrlea tfrlae tfrela
tfreal tfrael tfrale teaflr teafrl tealfr tealrf tearlf tearfl tefalr tefarl
teflar teflra tefrla tefral telfar telfra telafr telarf telraf telrfa terfla
terfal terlfa terlaf teralf terafl trafel trafle traefl traelf tralef tralfe
trfael trfale trfeal trfela trflea trflae trefal trefla treafl trealf trelaf
trelfa trlfea trlfae trlefa trleaf trlaef trlafe elatfr elatrf elaftr elafrt
elarft elartf eltafr eltarf eltfar eltfra eltrfa eltraf elftar elftra elfatr
elfart elfrat elfrta elrtfa elrtaf elrfta elrfat elraft elratf ealtfr ealtrf
ealftr ealfrt ealrft ealrtf eatlfr eatlrf eatflr eatfrl eatrfl eatrlf eaftlr
eaftrl eafltr eaflrt eafrlt eafrtl eartfl eartlf earftl earflt earlft earltf
etalfr etalrf etaflr etafrl etarfl etarlf etlafr etlarf etlfar etlfra etlrfa
etlraf etflar etflra etfalr etfarl etfral etfrla etrlfa etrlaf etrfla etrfal
etrafl etralf efatlr efatrl efaltr efalrt efarlt efartl eftalr eftarl eftlar
eftlra eftrla eftral efltar efltra eflatr eflart eflrat eflrta efrtla efrtal
efrlta efrlat efralt efratl eratfl eratlf eraftl eraflt eralft eraltf ertafl
ertalf ertfal ertfla ertlfa ertlaf erftal erftla erfatl erfalt erflat erflta
erltfa erltaf erlfta erlfat erlaft erlatf rlatef rlatfe rlaetf rlaeft rlafet
rlafte rltaef rltafe rlteaf rltefa rltfea rltfae rletaf rletfa rleatf rleaft
rlefat rlefta rlftea rlftae rlfeta rlfeat rlfaet rlfate raltef raltfe raletf
raleft ralfet ralfte ratlef ratlfe ratelf ratefl ratfel ratfle raetlf raetfl
raeltf raelft raeflt raeftl raftel raftle rafetl rafelt raflet raflte rtalef
rtalfe rtaelf rtaefl rtafel rtafle rtlaef rtlafe rtleaf rtlefa rtlfea rtlfae
rtelaf rtelfa rtealf rteafl rtefal rtefla rtflea rtflae rtfela rtfeal rtfael
rtfale reatlf reatfl realtf realft reaflt reaftl retalf retafl retlaf retlfa
retfla retfal reltaf reltfa relatf relaft relfat relfta reftla reftal reflta
reflat refalt refatl rfatel rfatle rfaetl rfaelt rfalet rfalte rftael rftale
rfteal rftela rftlea rftlae rfetal rfetla rfeatl rfealt rfelat rfelta rfltea
rfltae rfleta rfleat rflaet rflate

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History of cryptography
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