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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: damone
cipher variations:
ebnpof fcoqpg gdprqh heqsri ifrtsj
jgsutk khtvul liuwvm mjvxwn nkwyxo
olxzyp pmyazq qnzbar roacbs spbdct
tqcedu urdfev vsegfw wtfhgx xugihy
yvhjiz zwikja axjlkb bykmlc czlnmd

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: damone
Cipher: wznlmv

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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: damone

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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: damone
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: damone
Cipher: qnzbar

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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: damone
Cipher: 411123433351

Extended Methods:
Method #1

Plaintext: damone
method variations:

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

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Method #3

Plaintext: damone
method variations:
afsnxq fsnxqa snxqaf
nxqafs xqafsn qafsnx

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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: damone

all 720 cipher variations:
damone damoen damnoe damneo dameno dameon daomne daomen daonme daonem daoenm
daoemn danome danoem danmoe danmeo danemo daneom daeonm daeomn daenom daenmo
daemno daemon dmaone dmaoen dmanoe dmaneo dmaeno dmaeon dmoane dmoaen dmonae
dmonea dmoena dmoean dmnoae dmnoea dmnaoe dmnaeo dmneao dmneoa dmeona dmeoan
dmenoa dmenao dmeano dmeaon domane domaen domnae domnea domena domean doamne
doamen doanme doanem doaenm doaemn doname donaem donmae donmea donema doneam
doeanm doeamn doenam doenma doemna doeman dnmoae dnmoea dnmaoe dnmaeo dnmeao
dnmeoa dnomae dnomea dnoame dnoaem dnoeam dnoema dnaome dnaoem dnamoe dnameo
dnaemo dnaeom dneoam dneoma dneaom dneamo dnemao dnemoa demona demoan demnoa
demnao demano demaon deomna deoman deonma deonam deoanm deoamn denoma denoam
denmoa denmao denamo denaom deaonm deaomn deanom deanmo deamno deamon admone
admoen admnoe admneo admeno admeon adomne adomen adonme adonem adoenm adoemn
adnome adnoem adnmoe adnmeo adnemo adneom adeonm adeomn adenom adenmo ademno
ademon amdone amdoen amdnoe amdneo amdeno amdeon amodne amoden amonde amoned
amoend amoedn amnode amnoed amndoe amndeo amnedo amneod ameond ameodn amenod
amendo amedno amedon aomdne aomden aomnde aomned aomend aomedn aodmne aodmen
aodnme aodnem aodenm aodemn aondme aondem aonmde aonmed aonemd aonedm aoednm
aoedmn aoendm aoenmd aoemnd aoemdn anmode anmoed anmdoe anmdeo anmedo anmeod
anomde anomed anodme anodem anoedm anoemd andome andoem andmoe andmeo andemo
andeom aneodm aneomd anedom anedmo anemdo anemod aemond aemodn aemnod aemndo
aemdno aemdon aeomnd aeomdn aeonmd aeondm aeodnm aeodmn aenomd aenodm aenmod
aenmdo aendmo aendom aedonm aedomn aednom aednmo aedmno aedmon madone madoen
madnoe madneo madeno madeon maodne maoden maonde maoned maoend maoedn manode
manoed mandoe mandeo manedo maneod maeond maeodn maenod maendo maedno maedon
mdaone mdaoen mdanoe mdaneo mdaeno mdaeon mdoane mdoaen mdonae mdonea mdoena
mdoean mdnoae mdnoea mdnaoe mdnaeo mdneao mdneoa mdeona mdeoan mdenoa mdenao
mdeano mdeaon modane modaen modnae modnea modena modean moadne moaden moande
moaned moaend moaedn monade monaed mondae mondea moneda monead moeand moeadn
moenad moenda moedna moedan mndoae mndoea mndaoe mndaeo mndeao mndeoa mnodae
mnodea mnoade mnoaed mnoead mnoeda mnaode mnaoed mnadoe mnadeo mnaedo mnaeod
mneoad mneoda mneaod mneado mnedao mnedoa medona medoan mednoa mednao medano
medaon meodna meodan meonda meonad meoand meoadn menoda menoad mendoa mendao
menado menaod meaond meaodn meanod meando meadno meadon oamdne oamden oamnde
oamned oamend oamedn oadmne oadmen oadnme oadnem oadenm oademn oandme oandem
oanmde oanmed oanemd oanedm oaednm oaedmn oaendm oaenmd oaemnd oaemdn omadne
omaden omande omaned omaend omaedn omdane omdaen omdnae omdnea omdena omdean
omndae omndea omnade omnaed omnead omneda omedna omedan omenda omenad omeand
omeadn odmane odmaen odmnae odmnea odmena odmean odamne odamen odanme odanem
odaenm odaemn odname odnaem odnmae odnmea odnema odneam odeanm odeamn odenam
odenma odemna odeman onmdae onmdea onmade onmaed onmead onmeda ondmae ondmea
ondame ondaem ondeam ondema onadme onadem onamde onamed onaemd onaedm onedam
onedma oneadm oneamd onemad onemda oemdna oemdan oemnda oemnad oemand oemadn
oedmna oedman oednma oednam oedanm oedamn oendma oendam oenmda oenmad oenamd
oenadm oeadnm oeadmn oeandm oeanmd oeamnd oeamdn namode namoed namdoe namdeo
namedo nameod naomde naomed naodme naodem naoedm naoemd nadome nadoem nadmoe
nadmeo nademo nadeom naeodm naeomd naedom naedmo naemdo naemod nmaode nmaoed
nmadoe nmadeo nmaedo nmaeod nmoade nmoaed nmodae nmodea nmoeda nmoead nmdoae
nmdoea nmdaoe nmdaeo nmdeao nmdeoa nmeoda nmeoad nmedoa nmedao nmeado nmeaod
nomade nomaed nomdae nomdea nomeda nomead noamde noamed noadme noadem noaedm
noaemd nodame nodaem nodmae nodmea nodema nodeam noeadm noeamd noedam noedma
noemda noemad ndmoae ndmoea ndmaoe ndmaeo ndmeao ndmeoa ndomae ndomea ndoame
ndoaem ndoeam ndoema ndaome ndaoem ndamoe ndameo ndaemo ndaeom ndeoam ndeoma
ndeaom ndeamo ndemao ndemoa nemoda nemoad nemdoa nemdao nemado nemaod neomda
neomad neodma neodam neoadm neoamd nedoma nedoam nedmoa nedmao nedamo nedaom
neaodm neaomd neadom neadmo neamdo neamod eamond eamodn eamnod eamndo eamdno
eamdon eaomnd eaomdn eaonmd eaondm eaodnm eaodmn eanomd eanodm eanmod eanmdo
eandmo eandom eadonm eadomn eadnom eadnmo eadmno eadmon emaond emaodn emanod
emando emadno emadon emoand emoadn emonad emonda emodna emodan emnoad emnoda
emnaod emnado emndao emndoa emdona emdoan emdnoa emdnao emdano emdaon eomand
eomadn eomnad eomnda eomdna eomdan eoamnd eoamdn eoanmd eoandm eoadnm eoadmn
eonamd eonadm eonmad eonmda eondma eondam eodanm eodamn eodnam eodnma eodmna
eodman enmoad enmoda enmaod enmado enmdao enmdoa enomad enomda enoamd enoadm
enodam enodma enaomd enaodm enamod enamdo enadmo enadom endoam endoma endaom
endamo endmao endmoa edmona edmoan edmnoa edmnao edmano edmaon edomna edoman
edonma edonam edoanm edoamn ednoma ednoam ednmoa ednmao ednamo ednaom edaonm
edaomn edanom edanmo edamno edamon

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