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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: thring
cipher variations:
uisjoh vjtkpi wkulqj xlvmrk ymwnsl
znxotm aoypun bpzqvo cqarwp drbsxq
esctyr ftduzs guevat hvfwbu iwgxcv
jxhydw kyizex lzjafy makbgz nblcha
ocmdib pdnejc qeofkd rfpgle sgqhmf

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: thring
Cipher: gsirmt

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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: thring

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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: thring
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: thring
Cipher: guevat

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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: thring
Cipher: 443224423322

Extended Methods:
Method #1

Plaintext: thring
method variations:

Method #2
Bifid cipher
The message is converted to its coordinates in the usual manner, but they are written vertically beneath:
t h r i n g 
4 3 2 4 3 2 
4 2 4 2 3 2 
They are then read out in rows:
Then divided up into pairs again, and the pairs turned back into letters using the square:
Plain: thring
Cipher: orhiih

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Method #3

Plaintext: thring
method variations:
ogtmhr gtmhro tmhrog
mhrogt hrogtm rogtmh

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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: thring

all 720 cipher variations:
thring thrign thrnig thrngi thrgni thrgin thirng thirgn thinrg thingr thignr
thigrn thnirg thnigr thnrig thnrgi thngri thngir thginr thgirn thgnir thgnri
thgrni thgrin trhing trhign trhnig trhngi trhgni trhgin trihng trihgn trinhg
tringh trignh trighn trnihg trnigh trnhig trnhgi trnghi trngih trginh trgihn
trgnih trgnhi trghni trghin tirhng tirhgn tirnhg tirngh tirgnh tirghn tihrng
tihrgn tihnrg tihngr tihgnr tihgrn tinhrg tinhgr tinrhg tinrgh tingrh tinghr
tighnr tighrn tignhr tignrh tigrnh tigrhn tnrihg tnrigh tnrhig tnrhgi tnrghi
tnrgih tnirhg tnirgh tnihrg tnihgr tnighr tnigrh tnhirg tnhigr tnhrig tnhrgi
tnhgri tnhgir tngihr tngirh tnghir tnghri tngrhi tngrih tgrinh tgrihn tgrnih
tgrnhi tgrhni tgrhin tgirnh tgirhn tginrh tginhr tgihnr tgihrn tgnirh tgnihr
tgnrih tgnrhi tgnhri tgnhir tghinr tghirn tghnir tghnri tghrni tghrin htring
htrign htrnig htrngi htrgni htrgin htirng htirgn htinrg htingr htignr htigrn
htnirg htnigr htnrig htnrgi htngri htngir htginr htgirn htgnir htgnri htgrni
htgrin hrting hrtign hrtnig hrtngi hrtgni hrtgin hritng hritgn hrintg hringt
hrignt hrigtn hrnitg hrnigt hrntig hrntgi hrngti hrngit hrgint hrgitn hrgnit
hrgnti hrgtni hrgtin hirtng hirtgn hirntg hirngt hirgnt hirgtn hitrng hitrgn
hitnrg hitngr hitgnr hitgrn hintrg hintgr hinrtg hinrgt hingrt hingtr higtnr
higtrn higntr hignrt higrnt higrtn hnritg hnrigt hnrtig hnrtgi hnrgti hnrgit
hnirtg hnirgt hnitrg hnitgr hnigtr hnigrt hntirg hntigr hntrig hntrgi hntgri
hntgir hngitr hngirt hngtir hngtri hngrti hngrit hgrint hgritn hgrnit hgrnti
hgrtni hgrtin hgirnt hgirtn hginrt hgintr hgitnr hgitrn hgnirt hgnitr hgnrit
hgnrti hgntri hgntir hgtinr hgtirn hgtnir hgtnri hgtrni hgtrin rhting rhtign
rhtnig rhtngi rhtgni rhtgin rhitng rhitgn rhintg rhingt rhignt rhigtn rhnitg
rhnigt rhntig rhntgi rhngti rhngit rhgint rhgitn rhgnit rhgnti rhgtni rhgtin
rthing rthign rthnig rthngi rthgni rthgin rtihng rtihgn rtinhg rtingh rtignh
rtighn rtnihg rtnigh rtnhig rtnhgi rtnghi rtngih rtginh rtgihn rtgnih rtgnhi
rtghni rtghin rithng rithgn ritnhg ritngh ritgnh ritghn rihtng rihtgn rihntg
rihngt rihgnt rihgtn rinhtg rinhgt rinthg rintgh ringth ringht righnt rightn
rignht rignth rigtnh rigthn rntihg rntigh rnthig rnthgi rntghi rntgih rnithg
rnitgh rnihtg rnihgt rnight rnigth rnhitg rnhigt rnhtig rnhtgi rnhgti rnhgit
rngiht rngith rnghit rnghti rngthi rngtih rgtinh rgtihn rgtnih rgtnhi rgthni
rgthin rgitnh rgithn rginth rginht rgihnt rgihtn rgnith rgniht rgntih rgnthi
rgnhti rgnhit rghint rghitn rghnit rghnti rghtni rghtin ihrtng ihrtgn ihrntg
ihrngt ihrgnt ihrgtn ihtrng ihtrgn ihtnrg ihtngr ihtgnr ihtgrn ihntrg ihntgr
ihnrtg ihnrgt ihngrt ihngtr ihgtnr ihgtrn ihgntr ihgnrt ihgrnt ihgrtn irhtng
irhtgn irhntg irhngt irhgnt irhgtn irthng irthgn irtnhg irtngh irtgnh irtghn
irnthg irntgh irnhtg irnhgt irnght irngth irgtnh irgthn irgnth irgnht irghnt
irghtn itrhng itrhgn itrnhg itrngh itrgnh itrghn ithrng ithrgn ithnrg ithngr
ithgnr ithgrn itnhrg itnhgr itnrhg itnrgh itngrh itnghr itghnr itghrn itgnhr
itgnrh itgrnh itgrhn inrthg inrtgh inrhtg inrhgt inrght inrgth intrhg intrgh
inthrg inthgr intghr intgrh inhtrg inhtgr inhrtg inhrgt inhgrt inhgtr ingthr
ingtrh inghtr inghrt ingrht ingrth igrtnh igrthn igrnth igrnht igrhnt igrhtn
igtrnh igtrhn igtnrh igtnhr igthnr igthrn igntrh ignthr ignrth ignrht ignhrt
ignhtr ightnr ightrn ighntr ighnrt ighrnt ighrtn nhritg nhrigt nhrtig nhrtgi
nhrgti nhrgit nhirtg nhirgt nhitrg nhitgr nhigtr nhigrt nhtirg nhtigr nhtrig
nhtrgi nhtgri nhtgir nhgitr nhgirt nhgtir nhgtri nhgrti nhgrit nrhitg nrhigt
nrhtig nrhtgi nrhgti nrhgit nrihtg nrihgt nrithg nritgh nrigth nright nrtihg
nrtigh nrthig nrthgi nrtghi nrtgih nrgith nrgiht nrgtih nrgthi nrghti nrghit
nirhtg nirhgt nirthg nirtgh nirgth nirght nihrtg nihrgt nihtrg nihtgr nihgtr
nihgrt nithrg nithgr nitrhg nitrgh nitgrh nitghr nightr nighrt nigthr nigtrh
nigrth nigrht ntrihg ntrigh ntrhig ntrhgi ntrghi ntrgih ntirhg ntirgh ntihrg
ntihgr ntighr ntigrh nthirg nthigr nthrig nthrgi nthgri nthgir ntgihr ntgirh
ntghir ntghri ntgrhi ntgrih ngrith ngriht ngrtih ngrthi ngrhti ngrhit ngirth
ngirht ngitrh ngithr ngihtr ngihrt ngtirh ngtihr ngtrih ngtrhi ngthri ngthir
nghitr nghirt nghtir nghtri nghrti nghrit ghrint ghritn ghrnit ghrnti ghrtni
ghrtin ghirnt ghirtn ghinrt ghintr ghitnr ghitrn ghnirt ghnitr ghnrit ghnrti
ghntri ghntir ghtinr ghtirn ghtnir ghtnri ghtrni ghtrin grhint grhitn grhnit
grhnti grhtni grhtin grihnt grihtn grinht grinth gritnh grithn grniht grnith
grnhit grnhti grnthi grntih grtinh grtihn grtnih grtnhi grthni grthin girhnt
girhtn girnht girnth girtnh girthn gihrnt gihrtn gihnrt gihntr gihtnr gihtrn
ginhrt ginhtr ginrht ginrth gintrh ginthr githnr githrn gitnhr gitnrh gitrnh
gitrhn gnriht gnrith gnrhit gnrhti gnrthi gnrtih gnirht gnirth gnihrt gnihtr
gnithr gnitrh gnhirt gnhitr gnhrit gnhrti gnhtri gnhtir gntihr gntirh gnthir
gnthri gntrhi gntrih gtrinh gtrihn gtrnih gtrnhi gtrhni gtrhin gtirnh gtirhn
gtinrh gtinhr gtihnr gtihrn gtnirh gtnihr gtnrih gtnrhi gtnhri gtnhir gthinr
gthirn gthnir gthnri gthrni gthrin

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