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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: harems
cipher variations:
ibsfnt jctgou kduhpv leviqw mfwjrx
ngxksy ohyltz pizmua qjanvb rkbowc
slcpxd tmdqye unerzf vofsag wpgtbh
xqhuci yrivdj zsjwek atkxfl bulygm
cvmzhn dwnaio exobjp fypckq gzqdlr

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: harems
Cipher: szivnh

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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: harems

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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: harems
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: harems
Cipher: unerzf

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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: harems
Cipher: 321124512334

Extended Methods:
Method #1

Plaintext: harems
method variations:

Method #2
Bifid cipher
The message is converted to its coordinates in the usual manner, but they are written vertically beneath:
h a r e m s 
3 1 2 5 2 3 
2 1 4 1 3 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: harems
Cipher: cwmbds

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Method #3

Plaintext: harems
method variations:
bfyfno fyfnob yfnobf
fnobfy nobfyf obfyfn

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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: harems

all 720 cipher variations:
harems haresm harmes harmse harsme harsem haerms haersm haemrs haemsr haesmr
haesrm hamers hamesr hamres hamrse hamsre hamser hasemr haserm hasmer hasmre
hasrme hasrem hraems hraesm hrames hramse hrasme hrasem hreams hreasm hremas
hremsa hresma hresam hrmeas hrmesa hrmaes hrmase hrmsae hrmsea hrsema hrseam
hrsmea hrsmae hrsame hrsaem herams herasm hermas hermsa hersma hersam hearms
hearsm heamrs heamsr heasmr heasrm hemars hemasr hemras hemrsa hemsra hemsar
hesamr hesarm hesmar hesmra hesrma hesram hmreas hmresa hmraes hmrase hmrsae
hmrsea hmeras hmersa hmears hmeasr hmesar hmesra hmaers hmaesr hmares hmarse
hmasre hmaser hmsear hmsera hmsaer hmsare hmsrae hmsrea hsrema hsream hsrmea
hsrmae hsrame hsraem hserma hseram hsemra hsemar hseamr hsearm hsmera hsmear
hsmrea hsmrae hsmare hsmaer hsaemr hsaerm hsamer hsamre hsarme hsarem ahrems
ahresm ahrmes ahrmse ahrsme ahrsem aherms ahersm ahemrs ahemsr ahesmr ahesrm
ahmers ahmesr ahmres ahmrse ahmsre ahmser ahsemr ahserm ahsmer ahsmre ahsrme
ahsrem arhems arhesm arhmes arhmse arhsme arhsem arehms arehsm aremhs aremsh
aresmh areshm armehs armesh armhes armhse armshe armseh arsemh arsehm arsmeh
arsmhe arshme arshem aerhms aerhsm aermhs aermsh aersmh aershm aehrms aehrsm
aehmrs aehmsr aehsmr aehsrm aemhrs aemhsr aemrhs aemrsh aemsrh aemshr aeshmr
aeshrm aesmhr aesmrh aesrmh aesrhm amrehs amresh amrhes amrhse amrshe amrseh
amerhs amersh amehrs amehsr ameshr amesrh amhers amhesr amhres amhrse amhsre
amhser amsehr amserh amsher amshre amsrhe amsreh asremh asrehm asrmeh asrmhe
asrhme asrhem asermh aserhm asemrh asemhr asehmr asehrm asmerh asmehr asmreh
asmrhe asmhre asmher ashemr asherm ashmer ashmre ashrme ashrem rahems rahesm
rahmes rahmse rahsme rahsem raehms raehsm raemhs raemsh raesmh raeshm ramehs
ramesh ramhes ramhse ramshe ramseh rasemh rasehm rasmeh rasmhe rashme rashem
rhaems rhaesm rhames rhamse rhasme rhasem rheams rheasm rhemas rhemsa rhesma
rhesam rhmeas rhmesa rhmaes rhmase rhmsae rhmsea rhsema rhseam rhsmea rhsmae
rhsame rhsaem rehams rehasm rehmas rehmsa rehsma rehsam reahms reahsm reamhs
reamsh reasmh reashm remahs remash remhas remhsa remsha remsah resamh resahm
resmah resmha reshma resham rmheas rmhesa rmhaes rmhase rmhsae rmhsea rmehas
rmehsa rmeahs rmeash rmesah rmesha rmaehs rmaesh rmahes rmahse rmashe rmaseh
rmseah rmseha rmsaeh rmsahe rmshae rmshea rshema rsheam rshmea rshmae rshame
rshaem rsehma rseham rsemha rsemah rseamh rseahm rsmeha rsmeah rsmhea rsmhae
rsmahe rsmaeh rsaemh rsaehm rsameh rsamhe rsahme rsahem earhms earhsm earmhs
earmsh earsmh earshm eahrms eahrsm eahmrs eahmsr eahsmr eahsrm eamhrs eamhsr
eamrhs eamrsh eamsrh eamshr eashmr eashrm easmhr easmrh easrmh easrhm erahms
erahsm eramhs eramsh erasmh erashm erhams erhasm erhmas erhmsa erhsma erhsam
ermhas ermhsa ermahs ermash ermsah ermsha ershma ersham ersmha ersmah ersamh
ersahm ehrams ehrasm ehrmas ehrmsa ehrsma ehrsam eharms eharsm ehamrs ehamsr
ehasmr ehasrm ehmars ehmasr ehmras ehmrsa ehmsra ehmsar ehsamr ehsarm ehsmar
ehsmra ehsrma ehsram emrhas emrhsa emrahs emrash emrsah emrsha emhras emhrsa
emhars emhasr emhsar emhsra emahrs emahsr emarhs emarsh emasrh emashr emshar
emshra emsahr emsarh emsrah emsrha esrhma esrham esrmha esrmah esramh esrahm
eshrma eshram eshmra eshmar eshamr esharm esmhra esmhar esmrha esmrah esmarh
esmahr esahmr esahrm esamhr esamrh esarmh esarhm marehs maresh marhes marhse
marshe marseh maerhs maersh maehrs maehsr maeshr maesrh mahers mahesr mahres
mahrse mahsre mahser masehr maserh masher mashre masrhe masreh mraehs mraesh
mrahes mrahse mrashe mraseh mreahs mreash mrehas mrehsa mresha mresah mrheas
mrhesa mrhaes mrhase mrhsae mrhsea mrseha mrseah mrshea mrshae mrsahe mrsaeh
merahs merash merhas merhsa mersha mersah mearhs mearsh meahrs meahsr meashr
measrh mehars mehasr mehras mehrsa mehsra mehsar mesahr mesarh meshar meshra
mesrha mesrah mhreas mhresa mhraes mhrase mhrsae mhrsea mheras mhersa mhears
mheasr mhesar mhesra mhaers mhaesr mhares mharse mhasre mhaser mhsear mhsera
mhsaer mhsare mhsrae mhsrea msreha msreah msrhea msrhae msrahe msraeh mserha
mserah msehra msehar mseahr msearh mshera mshear mshrea mshrae mshare mshaer
msaehr msaerh msaher msahre msarhe msareh saremh sarehm sarmeh sarmhe sarhme
sarhem saermh saerhm saemrh saemhr saehmr saehrm samerh samehr samreh samrhe
samhre samher sahemr saherm sahmer sahmre sahrme sahrem sraemh sraehm srameh
sramhe srahme srahem sreamh sreahm sremah sremha srehma sreham srmeah srmeha
srmaeh srmahe srmhae srmhea srhema srheam srhmea srhmae srhame srhaem seramh
serahm sermah sermha serhma serham searmh searhm seamrh seamhr seahmr seahrm
semarh semahr semrah semrha semhra semhar sehamr seharm sehmar sehmra sehrma
sehram smreah smreha smraeh smrahe smrhae smrhea smerah smerha smearh smeahr
smehar smehra smaerh smaehr smareh smarhe smahre smaher smhear smhera smhaer
smhare smhrae smhrea shrema shream shrmea shrmae shrame shraem sherma sheram
shemra shemar sheamr shearm shmera shmear shmrea shmrae shmare shmaer shaemr
shaerm shamer shamre sharme sharem

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History of cryptography
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